old hat UK /ˌəʊl(d)ˈhæt/US /ˌoʊl(d)ˈhæt/noun 4adjective 1forms 3 noun4 •Something regarded as very familiar and unoriginal, hackneyed, or out of date.Oliver. What was the address about, to begin with? / Willie. Oh, the same old hat—Freedom. — 1920 •(slang, no longer used) The female genitalia.I shall conclude this learned Note vvith remarking, that the Term Old Hat, is at present used by the Vulgar, in no very honourable Sense. — 1743 •(offensive, no longer used) A woman treated as a sexual partner.VVhy, hovv novv, ye piece of old Hat, vvhat are ye musty? the Jade's as musty as a stale pot of Marmalade of her ovvn making. — 1697 •(slang, no longer used) Sexual intercourse. adjective1 •Very familiar and unoriginal; common, hackneyed, out of date.[Noël] Coward is such an old hand at this kind of thing that he makes it seem old hat. — 1946 formsold hats · more old hat · most old hat