denounce

(verb) speak out against. Example: "He denounced the nazis."

(verb) to accuse or condemn or openly or formally or brand as disgraceful. Synonyms: stigmatize, stigmatise, brand, mark. Examples: "He denounced the government action." "She was stigmatized by society because she had a child out of wedlock."

(verb) announce the termination of, as of treaties.

(verb) give away information about somebody. Synonyms: tell on, betray, give away, rat, grass, shit, shop, snitch, stag. Example: "He told on his classmate who had cheated on the exam."