WordWeb Online

1. Speak out against
   "He denounced the Nazis"
    
2. Accuse or condemn openly or formally; classify or describe as disgraceful
   "He denounced the government action";
   - stigmatize, stigmatise [Brit], brand, mark
    
3. Announce the termination of, as of treaties
    
4. Give away information about somebody
   "He denounced his classmate who had cheated on the exam";
   - tell on, betray, give away, rat, grass, shop, snitch, stag, squeak

Derived forms: denounces, denounced, denouncing

Type of: announce, criticise [Brit], criticize, damn, denote, inform, knock, label, pick apart