Fat Lip Meaning

(idiomatic) A swelling on the lip, especially one resulting from a punch or other blow.

Example: 1966 31 Jan., Abigail Van Buren, "Dear Abby: You Can't Reform Dad," Columbia Missourian, p. 9:
  He has a very ugly temper, and I have to be careful what I say to him or I'll end up with a fat lip.