noun Chiefly British Informal.
Examples from the Web for billycock
And beside this hole, little the worse for five weeks in the open, lay Joe Gregory's billycock hat.The Torch and Other Tales|Eden Phillpotts
I am heartbroken to think that I have not won the esteem of that lady in the billycock hat.
He was conspicuous generally for light-coloured close-fitting garments and for a billycock hat.The American Senator|Anthony Trollope
I had noted the hats of that elect assemblage, and there had not been a billycock among them.The Record of Nicholas Freydon|A. J. (Alec John) Dawson
Wear your billycock at the back of your head, as it will break your falls.