Definition & Meaning of "ass-licking"in English

What is the origin of the term "ass-licking" and how is it used?

Ass-licking is a slang term that appeared in mid-20th-century English to describe the act of excessively praising or flattering someone to gain favor or advantage. The term comes from the literal image of "licking someone's ass," used as a metaphor for being overly eager to please. Historically, it was derogatory, meant to criticize or mock people for insincere or greedy flattery. Today it remains vulgar and insulting, and its use is generally limited to informal, critical, or rude contexts rather than polite or neutral conversation.