Definition & Meaning of "ass-licker"in English

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

Ass-licker is a slang compound noun that appeared in mid-20th-century English to describe a person who flatters others too much to get something from them. The term comes from the literal image of "licking someone's ass," used as a metaphor for being overly eager to please or gain favor. Historically, it was derogatory, meant to make fun of or insult someone for being overly flattering. Today it remains vulgar and insulting, and is generally used only in informal, critical, or rude contexts rather than polite conversation.