old-hat vs threadbare

old-hat and threadbare both are adjectives.

Word	Noun	Adjective	Verb	Adverb
old-hat	No	Yes	No	No
threadbare	No	Yes	No	No

As adjectives, old-hat and threadbare are synonyms defined as:

old-hat and threadbare: repeated too often; overfamiliar through overuse

Other synonyms of old-hat include banal, commonplace, hackneyed, shopworn, stock, timeworn, tired, trite, well-worn.

old-hat (adjective)	threadbare (adjective)
out of fashion	repeated too often; overfamiliar through overuse
repeated too often; overfamiliar through overuse	having the nap worn away so that the threads show through