Fig. a dog; dogs in general. Man's best friend just peed all over my shoes! McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc. an affectionate or humorous way of referring to a dog. Farlex Partner Idioms Dictionary © Farlex 2017

Man's best friend definition: a dog, especially as a pet.. See examples of MAN'S BEST FRIEND used in a sentence.