The Collaborative International Dictionary of English v.0.48:
Bonnet \Bon"net\ (b[o^]n"n[e^]t), n. [OE. bonet, OF. bonet,
bonete. F. bonnet fr. LL. bonneta, bonetum; orig. the name of
a stuff, and of unknown origin.]
1. A headdress for men and boys; a cap. [Obs.] --Milton.
2. A soft, elastic, very durable cap, made of thick, seamless
woolen stuff, and worn by men in Scotland.
And plaids and bonnets waving high. --Sir W.
3. A covering for the head, worn by women, usually protecting
more or less the back and sides of the head, but no part
of the forehead. The shape of the bonnet varies greatly at
different times; formerly the front part projected, and
spread outward, like the mouth of a funnel.
4. Anything resembling a bonnet in shape or use; as,
(a) (Fort.) A small defense work at a salient angle; or a
part of a parapet elevated to screen the other part
from enfilade fire.
(b) A metallic canopy, or projection, over an opening, as
a fireplace, or a cowl or hood to increase the draught
of a chimney, etc.
(c) A frame of wire netting over a locomotive chimney, to
prevent escape of sparks.
(d) A roofing over the cage of a mine, to protect its
occupants from objects falling down the shaft.
(e) In pumps, a metal covering for the openings in the
5. (Naut.) An additional piece of canvas laced to the foot of
a jib or foresail in moderate winds. --Hakluyt.
6. The second stomach of a ruminating animal.
7. An accomplice of a gambler, auctioneer, etc., who entices
others to bet or to bid; a decoy. [Cant]
8. (Automobiles) The metal cover or shield over the motor;
predominantly British usage. In the U.S. it is called the
[Webster 1913 Suppl.]
Bonnet limpet (Zool.), a name given, from their shape, to
various species of shells (family Calyptr[ae]id[ae]).
Bonnet monkey (Zool.), an East Indian monkey (Macacus
sinicus), with a tuft of hair on its head; the munga.
Bonnet piece, a gold coin of the time of James V. of
Scotland, the king's head on which wears a bonnet. --Sir
To have a bee in the bonnet. See under Bee.
Black bonnet. See under Black.
Blue bonnet. See in the Vocabulary.