Apparently an alteration of earlier bully-cocked.
billycock (plural billycocks)
- (dated) A felt hat with a rounded crown, similar to a bowler.
- 1922, Virginia Woolf, Jacob's Room, Vintage Classics, paperback edition, page 68:
- All this blazed up and showed faces far back, round, pale, smooth, bearded, some with billycock hats [...].
- 1936, Djuna Barnes, Nightwood, Faber & Faber 2007, p. 56:
- the grandmother who, for some unknown reason, was dressed as a man, wearing a billycock and a corked moustache, ridiculous and plump in tight trousers and a red waistcoat [...].
- 1978, Lawrence Durrell, Livia, Faber & Faber 1992 (Avignon Quintet), p. 372:
- the increasing paralysis confined her to this steel trolley, pushed by a gloved attendant dressed in a billycock hat and a long grey dustcoat.