adjective
1.
a. : that is behind the times : old-fashioned , reactionary
in today's climate suffragism seems old hat — Helen B. Woodward
the very young still regarded the rather young as old hat — R.L.Duffus
b. : lacking in freshness : hackneyed , trite
a buyer's main problem is … dropping the trend before it becomes old hat — Fashion Accessories
accustomed to dismiss Dutch 17th century painting as old hat — Emily Genauer
2. : inferior to present methods or practices : dated , obsolete
the company's microwave loop … (coaxial cable is old hat now) — New Yorker
such crude methods are old hat — R.G.Spivack