- old-fashioned; dated.
- trite from having long been used or known.
Origin of old hat
- (postpositive) old-fashioned or trite
Word Origin and History for old hat
"out of date," first recorded 1911. As a noun phrase, however, it had different sense previously. The "Classical Dictionary of the Vulgar Tongue" (1796) defines it as, "a woman's privities, because frequently felt."
Obsolete, old-fashioned: “Get with it, Murray; your methods are strictly old hat.”