ˌold ˈhat BrE AmE adjective [not before noun]
if something is old hat, a lot of people have said or done the same thing before and it is therefore not new or interesting:
Most of this is probably old hat to you, isn’t it?
ˌold ˈhat BrE AmE adjective [not before noun]
if something is old hat, a lot of people have said or done the same thing before and it is therefore not new or interesting:
Most of this is probably old hat to you, isn’t it?
Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012