Definitions

1. noun

unwelcome or unwanted criticism or publicity, especially of a person or organization; a person who gives such criticism or publicity

“She became a media flack after her opinions on social media went viral.”

2. verb

to give unwanted or unwelcome criticism or publicity to (a person or organization); to criticize or comment on (something) in an unfavorable way

“The politician tried to flack her rival’s campaign promises, but it only made her look bad.”