what Quinion says is that the original word was bycoket,
quoating OED2 here:
a spurious word found in many dictionaries, originating in a misprint of BYCOKET

of which,
Also 5-6 byekoket, bycokett, bicokett; also erron. 6 abococket, -ed, abococke, 7 abacoc, 7-9 abacot. [a. OF. bicoquet, bicocquet, biquoquet, cap, casque, head-dress, ‘capuce, casaque à capuchon; habituellement, coiffure militaire; quelquefois parure de femme, chaperon’ (Godef.); dim. of F. bicoque = It. bicocca little castle on a hill, Sp. bicoca a lookout; probably the original meaning, as in the diminutives and derivatives, was some kind of cap, whence transf. to a structure, topping or ‘crowning’ a height. App. f. bi- twice + cocca as in cocca del capo ‘crown of the head’ (Florio). Cf. also Sp. bicoquin a cap with two peaks, bicoquete a peasant's cap, Piedm. bicochin a priest's cap (Diez).]

Through a remarkable series of blunders and ignorant reproductions of error, this word appears in modern dictionaries as ABACOT. In Hall's Chron. a bicocket appears to have been misprinted abococket, which was copied by Grafton, altered by Holinshed to abococke, and finally ‘improved’ by Abraham Fleming to abacot (perhaps through an intermediate abacoc); hence it was again copied by Baker, inserted in his Glossarium by Spelman, and thence copied by Phillips, and so handed down through Bailey, Ash, Todd, etc., to 19th century dictionaries (some of which provide a picture of the ‘abacot’), and even inserted in dictionaries of English and foreign languages. [EA]

your picture seems to be a crown, which this thing cap doesn't seem to be except for the 'crown of the head' part. OED does contain this note, which I don't find to be very helpful: (The two crowns [? of England and France] with which the bycoket of Henry VI was ‘garnished’ or ‘embroidered’, were, of course, no part of the ordinary bycoket.)

edit: here's an illlustration: link

Last edited by tsuwm; 03/12/09 10:17 PM.