- a man’s hat, worn especially in the 18th century, having a wide, stiff brim turned up on two or three sides toward a peaked crown.Compare bicorne, tricorn(def 2).
- knock into a cocked hat, Informal. to destroy completely; render unachievable.
- a hat with opposing brims turned up and caught together in order to give two points (bicorn) or three points (tricorn)
- knock into a cocked hat slang to outdo or defeat
Debunk, render useless or unbelievable. For example, His findings knocked our theory into a cocked hat. This expression alludes to a style of hat with the brim turned up on three sides—the three-cornered (tricorne) hat worn by officers in the American Revolution—giving it a distorted look. [Early 1800s]