diff --git a/packages/providers/src/__tests__/lexical-substitution.test.ts b/packages/providers/src/__tests__/lexical-substitution.test.ts
index b0ef812..25674c8 100644
--- a/packages/providers/src/__tests__/lexical-substitution.test.ts
+++ b/packages/providers/src/__tests__/lexical-substitution.test.ts
@@ -74,4 +74,25 @@ describe("applyLexicalSubstitution", () => {
     expect(result).toContain("zumo");
     expect(result).not.toContain("jugo");
   });
+
+  it("does not swap ambiguous slang terms with common non-slang meanings", () => {
+    // "botón" = button (UI) but also es-UY slang for "cop". Must NOT swap to "tomba".
+    expect(applyLexicalSubstitution("Haga clic en el botón para continuar.", "es-CO"))
+      .toContain("botón");
+
+    // "agente" = agent (generic) but also es-EC variant for "cop". Must NOT swap.
+    expect(applyLexicalSubstitution("El agente secreto fue descubierto.", "es-CO"))
+      .toContain("agente");
+
+    // "cuero" = leather but also es-DO slang for "money" and "cop". Must NOT swap.
+    expect(applyLexicalSubstitution("El cuero del zapato está dañado.", "es-CO"))
+      .toContain("cuero");
+  });
+
+  it("still swaps unambiguous slang terms correctly", () => {
+    // "paco" (es-CL cop slang) is unambiguous — should still swap
+    const result = applyLexicalSubstitution("El paco está en la esquina.", "es-CO");
+    expect(result).toContain("tomba");
+    expect(result).not.toContain("paco");
+  });
 });
diff --git a/packages/types/src/dialectal-dictionary.json b/packages/types/src/dialectal-dictionary.json
index 2197b00..83360bc 100644
--- a/packages/types/src/dialectal-dictionary.json
+++ b/packages/types/src/dialectal-dictionary.json
@@ -44897,7 +44897,8 @@
       "es-UY": {
         "term": "botón",
         "frequency": 1,
-        "register": "informal"
+        "register": "informal",
+        "ambiguous": true
       },
       "es-PY": {
         "term": "mbae",
@@ -44942,7 +44943,8 @@
       "es-EC": {
         "term": "agente",
         "frequency": 1,
-        "register": "universal"
+        "register": "universal",
+        "ambiguous": true
       },
       "es-BO": {
         "term": "choco",
@@ -44952,7 +44954,8 @@
       "es-DO": {
         "term": "cuero",
         "frequency": 1,
-        "register": "informal"
+        "register": "informal",
+        "ambiguous": true
       },
       "es-PR": {
         "term": "policía",
@@ -46001,7 +46004,8 @@
       "es-DO": {
         "term": "cuero",
         "frequency": 2,
-        "register": "informal"
+        "register": "informal",
+        "ambiguous": true
       },
       "es-PR": {
         "term": "chavos",
diff --git a/packages/types/src/dialectal-dictionary.ts b/packages/types/src/dialectal-dictionary.ts
index 49521c8..c84264f 100644
--- a/packages/types/src/dialectal-dictionary.ts
+++ b/packages/types/src/dialectal-dictionary.ts
@@ -19,6 +19,10 @@ export interface Variant {
   frequency: 1 | 2 | 3;
   register: "formal" | "informal" | "universal";
   notes?: string;
+  /** When true, this variant has a common non-slang meaning and should not
+   *  be used as an avoid-term for lexical substitution. Prevents false
+   *  positives like "botón" (button) being swapped to "tomba" (cop slang). */
+  ambiguous?: boolean;
 }
 
 export interface DictionaryEntry {
diff --git a/packages/types/src/dialectal-vocabulary.ts b/packages/types/src/dialectal-vocabulary.ts
index b556f92..e217946 100644
--- a/packages/types/src/dialectal-vocabulary.ts
+++ b/packages/types/src/dialectal-vocabulary.ts
@@ -73,7 +73,13 @@ export function getVocabularyForDialect(dialect: SpanishDialect): VocabularySwap
     const variant = resolveVariant(entry, dialect);
     if (!variant) continue;
     const allTerms = getAllTerms(entry);
-    const avoidTerms = allTerms.filter(t => t !== variant.term);
+    // Build avoid-terms, excluding ambiguous variants that have common
+    // non-slang meanings (e.g. "botón" = button, not just es-UY cop slang).
+    const ambiguousTerms = new Set<string>();
+    for (const v of Object.values(entry.variants ?? {})) {
+      if (v?.ambiguous) ambiguousTerms.add(v.term);
+    }
+    const avoidTerms = allTerms.filter(t => t !== variant.term && !ambiguousTerms.has(t));
     swaps.push({
       concept: entry.concept,
       englishGloss: entry.englishGloss,