Definition of "catchphrase"

Frequently, catch phrases are not, in the grammarians' sense, phrases at all, but sentences. Catch phrases, like the closely linked proverbial sayings, are self-contained, as, obviously, clichés are too. Catch phrases are usually more pointed and ‘human’ than clichés, although the former sometimes arises from, and often they generate, the latter. Occasionally, catch phrases stem from too famous quotations.

2003 , Eric Partridge, “Introduction to the First Editon”, in Paul Beale, editor, A Dictionary of Catch Phrases‎, 2nd edition, Routledge

For Tigger, he created a slight lisp and laugh, crediting his British wife with Tigger's "TTFN" catchprase - "ta-ta for now", itself coming from BBC radio comedy It's That Man Again.

2005 May 14, “Disney's Tigger voice dies at 82”, in BBC News website‎

The former head of BBC comedy claims catchphrases are out of fashion. But as Corporal Jones might say, ‘Don’t panic!’

2018 September 18, Brian Logan, “Catchphrase comedy is dead. Am I bovvered?”, in The Guardian‎