demode vs old-hat

demode and old-hat both are adjectives.

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

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

Other synonyms of demode include antique, ex, old-fashioned, outmoded, passe, passee.

demode (adjective)	old-hat (adjective)
out of fashion	out of fashion
	repeated too often; overfamiliar through overuse