diff --git a/crates/api/src/admin_vocab.rs b/crates/api/src/admin_vocab.rs
index 0b714e4..b8d60de 100644
--- a/crates/api/src/admin_vocab.rs
+++ b/crates/api/src/admin_vocab.rs
@@ -5,9 +5,10 @@ use axum::{
     Json, Router,
     extract::{Path, State},
     http::StatusCode,
+    response::{IntoResponse, Response},
     routing::get,
 };
-use domain::{AuditActor, LocalizedLabel, NewTerm, VocabularyId};
+use domain::{AuditActor, LocalizedLabel, NewTerm, TermId, VocabularyId};
 use serde::{Deserialize, Serialize};
 use utoipa::ToSchema;
 
@@ -221,6 +222,139 @@ pub(crate) async fn add_term(
     ))
 }
 
+/// 409 body: how many catalogue objects still reference the entity.
+#[derive(Serialize, ToSchema)]
+pub(crate) struct InUseView {
+    pub count: i64,
+}
+
+#[derive(Deserialize, ToSchema)]
+pub(crate) struct UpdateTermRequest {
+    pub external_uri: Option<String>,
+    pub labels: Vec<LabelInput>,
+}
+
+#[utoipa::path(
+    patch, path = "/api/admin/vocabularies/{id}/terms/{term_id}",
+    request_body = UpdateTermRequest,
+    params(
+        ("id" = String, Path, description = "Vocabulary id (UUID)"),
+        ("term_id" = String, Path, description = "Term id (UUID)")
+    ),
+    responses(
+        (status = 204),
+        (status = 401),
+        (status = 403),
+        (status = 404)
+    )
+)]
+pub(crate) async fn update_term(
+    auth: Authorized<EditCatalogue>,
+    State(state): State<AppState>,
+    Path((id, term_id)): Path<(String, String)>,
+    Json(req): Json<UpdateTermRequest>,
+) -> Result<StatusCode, StatusCode> {
+    let vocabulary_id = id
+        .parse::<VocabularyId>()
+        .map_err(|_| StatusCode::NOT_FOUND)?;
+
+    let term_id = term_id
+        .parse::<TermId>()
+        .map_err(|_| StatusCode::NOT_FOUND)?;
+
+    let labels: Vec<LocalizedLabel> = req
+        .labels
+        .into_iter()
+        .map(|l| LocalizedLabel {
+            lang: l.lang,
+            label: l.label,
+        })
+        .collect();
+
+    let mut tx = state
+        .db
+        .pool()
+        .begin()
+        .await
+        .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
+
+    let existed = db::vocab::update_term(
+        &mut tx,
+        AuditActor::User(auth.user.id.to_uuid()),
+        vocabulary_id,
+        term_id,
+        req.external_uri.as_deref(),
+        &labels,
+    )
+    .await
+    .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
+
+    if existed {
+        tx.commit()
+            .await
+            .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
+
+        Ok(StatusCode::NO_CONTENT)
+    } else {
+        Err(StatusCode::NOT_FOUND)
+    }
+}
+
+#[utoipa::path(
+    delete, path = "/api/admin/vocabularies/{id}/terms/{term_id}",
+    params(
+        ("id" = String, Path, description = "Vocabulary id (UUID)"),
+        ("term_id" = String, Path, description = "Term id (UUID)")
+    ),
+    responses(
+        (status = 204),
+        (status = 401),
+        (status = 403),
+        (status = 404),
+        (status = 409, body = InUseView, description = "Referenced by catalogue objects")
+    )
+)]
+pub(crate) async fn delete_term(
+    auth: Authorized<EditCatalogue>,
+    State(state): State<AppState>,
+    Path((id, term_id)): Path<(String, String)>,
+) -> Response {
+    let (Ok(vocab_id), Ok(term_id)) = (id.parse::<VocabularyId>(), term_id.parse::<TermId>())
+    else {
+        return StatusCode::NOT_FOUND.into_response();
+    };
+
+    let Ok(mut tx) = state.db.pool().begin().await else {
+        return StatusCode::INTERNAL_SERVER_ERROR.into_response();
+    };
+
+    let outcome = db::vocab::delete_term(
+        &mut tx,
+        AuditActor::User(auth.user.id.to_uuid()),
+        vocab_id,
+        term_id,
+    )
+    .await;
+
+    match outcome {
+        Ok(db::DeleteOutcome::Deleted) => match tx.commit().await {
+            Ok(()) => StatusCode::NO_CONTENT.into_response(),
+            Err(_) => StatusCode::INTERNAL_SERVER_ERROR.into_response(),
+        },
+        Ok(db::DeleteOutcome::InUse { count }) => {
+            let _ = tx.rollback().await;
+
+            (StatusCode::CONFLICT, Json(InUseView { count })).into_response()
+        }
+        Ok(db::DeleteOutcome::NotFound) => {
+            let _ = tx.rollback().await;
+
+            StatusCode::NOT_FOUND.into_response()
+        }
+        Err(_) => StatusCode::INTERNAL_SERVER_ERROR.into_response(),
+    }
+}
+
 pub(crate) fn routes() -> Router<AppState> {
     Router::new()
         .route(
@@ -231,4 +365,8 @@ pub(crate) fn routes() -> Router<AppState> {
             "/api/admin/vocabularies/{id}/terms",
             get(list_terms).post(add_term),
         )
+        .route(
+            "/api/admin/vocabularies/{id}/terms/{term_id}",
+            axum::routing::patch(update_term).delete(delete_term),
+        )
 }
diff --git a/crates/api/src/openapi.rs b/crates/api/src/openapi.rs
index b625cba..dcf2e99 100644
--- a/crates/api/src/openapi.rs
+++ b/crates/api/src/openapi.rs
@@ -31,6 +31,8 @@ use crate::{
         admin_vocab::create_vocabulary,
         admin_vocab::list_terms,
         admin_vocab::add_term,
+        admin_vocab::update_term,
+        admin_vocab::delete_term,
         admin_search::search_objects,
         admin_authorities::list_authorities,
         admin_authorities::create_authority
@@ -60,6 +62,8 @@ use crate::{
         admin_vocab::LabelInput,
         admin_vocab::TermView,
         admin_vocab::CreatedId,
+        admin_vocab::UpdateTermRequest,
+        admin_vocab::InUseView,
         admin_search::SearchHitView,
         admin_search::SearchResultsView,
         admin_authorities::AuthorityView,
diff --git a/crates/api/tests/admin_catalog.rs b/crates/api/tests/admin_catalog.rs
index 04aec01..336455f 100644
--- a/crates/api/tests/admin_catalog.rs
+++ b/crates/api/tests/admin_catalog.rs
@@ -333,3 +333,129 @@ async fn creating_a_vocabulary_writes_an_audit_entry(pool: PgPool) {
         "expected actor to be a user"
     );
 }
+
+async fn send(
+    app: &axum::Router,
+    cookie: &str,
+    method: &str,
+    uri: &str,
+    body: Option<&str>,
+) -> axum::http::Response<Body> {
+    let mut req = Request::builder()
+        .method(method)
+        .uri(uri)
+        .header(header::COOKIE, cookie);
+
+    if body.is_some() {
+        req = req.header(header::CONTENT_TYPE, "application/json");
+    }
+
+    let body = body
+        .map(|b| Body::from(b.to_owned()))
+        .unwrap_or_else(Body::empty);
+
+    app.clone().oneshot(req.body(body).unwrap()).await.unwrap()
+}
+
+#[sqlx::test(migrations = "../db/migrations")]
+async fn edit_and_delete_term(pool: PgPool) {
+    migrate_sessions(&db::Db::from_pool(pool.clone()))
+        .await
+        .unwrap();
+
+    seed_user(&pool, "ed@example.com", "pw-editor-123", Role::Editor).await;
+
+    let app = build_app(state(pool));
+    let cookie = login(&app, "ed@example.com", "pw-editor-123").await;
+
+    let v = send(
+        &app,
+        &cookie,
+        "POST",
+        "/api/admin/vocabularies",
+        Some(r#"{"key":"material"}"#),
+    )
+    .await;
+    let vid: serde_json::Value =
+        serde_json::from_slice(&v.into_body().collect().await.unwrap().to_bytes()).unwrap();
+    let vid = vid["id"].as_str().unwrap().to_owned();
+
+    let t = send(
+        &app,
+        &cookie,
+        "POST",
+        &format!("/api/admin/vocabularies/{vid}/terms"),
+        Some(r#"{"external_uri":null,"labels":[{"lang":"sv","label":"Trä"}]}"#),
+    )
+    .await;
+    let tid: serde_json::Value =
+        serde_json::from_slice(&t.into_body().collect().await.unwrap().to_bytes()).unwrap();
+    let tid = tid["id"].as_str().unwrap().to_owned();
+
+    let patched = send(
+        &app,
+        &cookie,
+        "PATCH",
+        &format!("/api/admin/vocabularies/{vid}/terms/{tid}"),
+        Some(r#"{"external_uri":"https://x","labels":[{"lang":"sv","label":"Träslag"}]}"#),
+    )
+    .await;
+    assert_eq!(patched.status(), StatusCode::NO_CONTENT);
+
+    let deleted = send(
+        &app,
+        &cookie,
+        "DELETE",
+        &format!("/api/admin/vocabularies/{vid}/terms/{tid}"),
+        None,
+    )
+    .await;
+    assert_eq!(deleted.status(), StatusCode::NO_CONTENT);
+
+    let again = send(
+        &app,
+        &cookie,
+        "DELETE",
+        &format!("/api/admin/vocabularies/{vid}/terms/{tid}"),
+        None,
+    )
+    .await;
+    assert_eq!(again.status(), StatusCode::NOT_FOUND);
+}
+
+#[sqlx::test(migrations = "../db/migrations")]
+async fn term_edit_delete_requires_auth(pool: PgPool) {
+    migrate_sessions(&db::Db::from_pool(pool.clone()))
+        .await
+        .unwrap();
+
+    let app = build_app(state(pool));
+    let term_uri = "/api/admin/vocabularies/00000000-0000-0000-0000-000000000000/terms/00000000-0000-0000-0000-000000000000";
+
+    let patch_resp = app
+        .clone()
+        .oneshot(
+            Request::builder()
+                .method("PATCH")
+                .uri(term_uri)
+                .header(header::CONTENT_TYPE, "application/json")
+                .body(Body::from(r#"{"labels":[]}"#))
+                .unwrap(),
+        )
+        .await
+        .unwrap();
+    assert_eq!(patch_resp.status(), StatusCode::UNAUTHORIZED);
+
+    let delete_resp = app
+        .clone()
+        .oneshot(
+            Request::builder()
+                .method("DELETE")
+                .uri(term_uri)
+                .body(Body::empty())
+                .unwrap(),
+        )
+        .await
+        .unwrap();
+    assert_eq!(delete_resp.status(), StatusCode::UNAUTHORIZED);
+}
diff --git a/crates/db/src/lib.rs b/crates/db/src/lib.rs
index 0f1c2fa..6db903f 100644
--- a/crates/db/src/lib.rs
+++ b/crates/db/src/lib.rs
@@ -10,6 +10,17 @@ pub mod vocab;
 
 use sqlx::postgres::{PgPool, PgPoolOptions};
 
+/// Result of a delete that catalogue-object references may block.
+#[derive(Debug, PartialEq, Eq)]
+pub enum DeleteOutcome {
+    /// The row was deleted.
+    Deleted,
+    /// Refused: `count` catalogue objects still reference it.
+    InUse { count: i64 },
+    /// The row did not exist.
+    NotFound,
+}
+
 /// A handle to the organization's PostgreSQL database.
 #[derive(Clone)]
 pub struct Db {
diff --git a/crates/db/src/vocab.rs b/crates/db/src/vocab.rs
index 9bc558a..681ef14 100644
--- a/crates/db/src/vocab.rs
+++ b/crates/db/src/vocab.rs
@@ -177,6 +177,122 @@ where
     Ok(found.map(|_| TermRef::new(term_id, vocabulary_id)))
 }
 
+/// Update a term's `external_uri` and labels (full replace), recording an `updated`
+/// audit entry. Returns `false` if no such term or the term does not belong to
+/// `vocabulary_id`. Pass a transaction connection.
+pub async fn update_term(
+    conn: &mut sqlx::PgConnection,
+    actor: AuditActor,
+    vocabulary_id: VocabularyId,
+    term_id: TermId,
+    external_uri: Option<&str>,
+    labels: &[LocalizedLabel],
+) -> Result<bool, sqlx::Error> {
+    let updated =
+        sqlx::query("UPDATE term SET external_uri = $2 WHERE id = $1 AND vocabulary_id = $3")
+            .bind(term_id.to_uuid())
+            .bind(external_uri)
+            .bind(vocabulary_id.to_uuid())
+            .execute(&mut *conn)
+            .await?
+            .rows_affected();
+
+    if updated == 0 {
+        return Ok(false);
+    }
+
+    sqlx::query("DELETE FROM term_label WHERE term_id = $1")
+        .bind(term_id.to_uuid())
+        .execute(&mut *conn)
+        .await?;
+
+    for label in labels {
+        sqlx::query("INSERT INTO term_label (term_id, lang, label) VALUES ($1, $2, $3)")
+            .bind(term_id.to_uuid())
+            .bind(&label.lang)
+            .bind(&label.label)
+            .execute(&mut *conn)
+            .await?;
+    }
+
+    audit::record(
+        &mut *conn,
+        &NewAuditEvent {
+            actor,
+            action: AuditAction::Updated,
+            entity_type: TERM_ENTITY_TYPE.to_owned(),
+            entity_id: term_id.to_uuid(),
+            changes: Vec::new(),
+        },
+    )
+    .await?;
+
+    Ok(true)
+}
+
+/// Count catalogue objects that reference `term_id` through a `term`-typed field.
+pub async fn count_objects_referencing_term<'e, E>(
+    executor: E,
+    term_id: TermId,
+) -> Result<i64, sqlx::Error>
+where
+    E: sqlx::PgExecutor<'e>,
+{
+    sqlx::query_scalar(
+        "SELECT count(*) FROM object o WHERE EXISTS ( \
+           SELECT 1 FROM field_definition fd \
+           WHERE fd.data_type = 'term' AND o.fields ->> fd.key = $1 )",
+    )
+    .bind(term_id.to_string())
+    .fetch_one(executor)
+    .await
+}
+
+/// Delete a term (its labels cascade) unless catalogue objects reference it, recording a
+/// `deleted` audit entry. Pass a transaction connection.
+pub async fn delete_term(
+    conn: &mut sqlx::PgConnection,
+    actor: AuditActor,
+    vocabulary_id: VocabularyId,
+    term_id: TermId,
+) -> Result<crate::DeleteOutcome, sqlx::Error> {
+    let exists =
+        sqlx::query_scalar::<_, i32>("SELECT 1 FROM term WHERE id = $1 AND vocabulary_id = $2")
+            .bind(term_id.to_uuid())
+            .bind(vocabulary_id.to_uuid())
+            .fetch_optional(&mut *conn)
+            .await?;
+
+    if exists.is_none() {
+        return Ok(crate::DeleteOutcome::NotFound);
+    }
+
+    let count = count_objects_referencing_term(&mut *conn, term_id).await?;
+
+    if count > 0 {
+        return Ok(crate::DeleteOutcome::InUse { count });
+    }
+
+    sqlx::query("DELETE FROM term WHERE id = $1")
+        .bind(term_id.to_uuid())
+        .execute(&mut *conn)
+        .await?;
+
+    audit::record(
+        &mut *conn,
+        &NewAuditEvent {
+            actor,
+            action: AuditAction::Deleted,
+            entity_type: TERM_ENTITY_TYPE.to_owned(),
+            entity_id: term_id.to_uuid(),
+            changes: Vec::new(),
+        },
+    )
+    .await?;
+
+    Ok(crate::DeleteOutcome::Deleted)
+}
+
 fn map_vocabulary(row: sqlx::postgres::PgRow) -> Result<Vocabulary, sqlx::Error> {
     Ok(Vocabulary {
         id: VocabularyId::from_uuid(row.try_get("id")?),
diff --git a/crates/db/tests/vocab.rs b/crates/db/tests/vocab.rs
index d3edabb..79564d3 100644
--- a/crates/db/tests/vocab.rs
+++ b/crates/db/tests/vocab.rs
@@ -1,5 +1,7 @@
-use db::{Db, vocab};
-use domain::{AuditActor, LocalizedLabel, NewTerm};
+use db::{Db, catalog, fields, vocab};
+use domain::{
+    AuditActor, FieldType, LocalizedLabel, NewFieldDefinition, NewTerm, ObjectInput, Visibility,
+};
 use sqlx::PgPool;
 
 #[sqlx::test]
@@ -169,3 +171,145 @@ async fn resolve_term_checks_vocabulary_membership(pool: PgPool) {
             .is_none()
     );
 }
+
+fn sample_object_input() -> ObjectInput {
+    ObjectInput {
+        object_number: "X.1".into(),
+        object_name: "Test".into(),
+        number_of_objects: 1,
+        brief_description: None,
+        current_location: None,
+        current_owner: None,
+        recorder: None,
+        recording_date: None,
+        visibility: Visibility::Draft,
+    }
+}
+
+#[sqlx::test(migrations = "../db/migrations")]
+async fn update_term_changes_labels_and_uri(pool: PgPool) {
+    let db = Db::from_pool(pool);
+    let mut tx = db.pool().begin().await.unwrap();
+    let vocab = vocab::create_vocabulary(&mut tx, AuditActor::System, "material")
+        .await
+        .unwrap();
+    let term_id = vocab::add_term(
+        &mut tx,
+        AuditActor::System,
+        &NewTerm {
+            vocabulary_id: vocab.id,
+            external_uri: None,
+            labels: vec![LocalizedLabel {
+                lang: "sv".into(),
+                label: "Trä".into(),
+            }],
+        },
+    )
+    .await
+    .unwrap();
+
+    let existed = vocab::update_term(
+        &mut tx,
+        AuditActor::System,
+        vocab.id,
+        term_id,
+        Some("https://example.org/wood"),
+        &[LocalizedLabel {
+            lang: "sv".into(),
+            label: "Träslag".into(),
+        }],
+    )
+    .await
+    .unwrap();
+    assert!(existed);
+    tx.commit().await.unwrap();
+
+    let term = vocab::term_by_id(db.pool(), term_id)
+        .await
+        .unwrap()
+        .unwrap();
+    assert_eq!(
+        term.external_uri.as_deref(),
+        Some("https://example.org/wood")
+    );
+    assert_eq!(term.labels.len(), 1);
+    assert_eq!(term.labels[0].label, "Träslag");
+}
+
+#[sqlx::test(migrations = "../db/migrations")]
+async fn delete_term_blocks_when_referenced_then_succeeds(pool: PgPool) {
+    use db::DeleteOutcome;
+
+    let db = Db::from_pool(pool);
+    let mut tx = db.pool().begin().await.unwrap();
+    let vocab = vocab::create_vocabulary(&mut tx, AuditActor::System, "material")
+        .await
+        .unwrap();
+    let term_id = vocab::add_term(
+        &mut tx,
+        AuditActor::System,
+        &NewTerm {
+            vocabulary_id: vocab.id,
+            external_uri: None,
+            labels: vec![LocalizedLabel {
+                lang: "sv".into(),
+                label: "Trä".into(),
+            }],
+        },
+    )
+    .await
+    .unwrap();
+
+    fields::create_field_definition(
+        &mut tx,
+        &NewFieldDefinition {
+            key: "material".into(),
+            field_type: FieldType::Term {
+                vocabulary_id: vocab.id,
+            },
+            required: false,
+            group_key: None,
+            labels: vec![LocalizedLabel {
+                lang: "sv".into(),
+                label: "Material".into(),
+            }],
+        },
+    )
+    .await
+    .unwrap();
+    let obj = catalog::create_object(&mut tx, AuditActor::System, &sample_object_input())
+        .await
+        .unwrap();
+    let mut map = serde_json::Map::new();
+    map.insert(
+        "material".into(),
+        serde_json::Value::String(term_id.to_string()),
+    );
+    catalog::set_object_fields(&mut tx, AuditActor::System, obj, &map)
+        .await
+        .unwrap();
+
+    let blocked = vocab::delete_term(&mut tx, AuditActor::System, vocab.id, term_id)
+        .await
+        .unwrap();
+    assert_eq!(blocked, DeleteOutcome::InUse { count: 1 });
+
+    catalog::set_object_fields(&mut tx, AuditActor::System, obj, &serde_json::Map::new())
+        .await
+        .unwrap();
+    let ok = vocab::delete_term(&mut tx, AuditActor::System, vocab.id, term_id)
+        .await
+        .unwrap();
+    assert_eq!(ok, DeleteOutcome::Deleted);
+    assert!(
+        vocab::term_by_id(&mut *tx, term_id)
+            .await
+            .unwrap()
+            .is_none()
+    );
+
+    let gone = vocab::delete_term(&mut tx, AuditActor::System, vocab.id, term_id)
+        .await
+        .unwrap();
+    assert_eq!(gone, DeleteOutcome::NotFound);
+}