From The Collaborative International Dictionary of English v.0.48 [gcide]:
old-hat \old-hat\ pred. adj.
same as old-fashioned, a., 2. [Narrower terms:
{unfashionable (vs. fashionable)}]
Syn: antique, old-fashioned, outmoded, out-of-date, passe,
passee.
[WordNet 1.5]
From WordNet (r) 3.0 (2006) [wn]:
old-hat
adj 1: repeated too often; overfamiliar through overuse;
"bromidic sermons"; "his remarks were trite and
commonplace"; "hackneyed phrases"; "a stock answer";
"repeating threadbare jokes"; "parroting some timeworn
axiom"; "the trite metaphor `hard as nails'" [syn:
banal, commonplace, hackneyed, old-hat,
shopworn, {stock(a)}, threadbare, timeworn,
tired, trite, well-worn]
2: out of fashion; "a suit of rather antique appearance";
"demode (or outmoded) attire"; "outmoded ideas" [syn:
antique, demode, ex, old-fashioned, {old-hat(p)},
outmoded, passe, passee]