1 a a woman's or child's hat tied under the chin and usu. with a brim framing the face. b a soft round brimless hat like a beret worn by men and boys in Scotland (cf. TAM-O'-SHANTER). c colloq. any hat.
2 Brit. a hinged cover over the engine of a motor vehicle.
3 the ceremonial feathered head-dress of an American Indian.
4 the cowl of a chimney etc.
5 a protective cap in various machines.
6 Naut. additional canvas laced to the foot of a sail.
Phrases and idioms:
bonnet monkey an Indian macaque, Macaca radiata, with a bonnet-like tuft of hair.
Derivatives:
bonneted adj.
Etymology: ME f. OF bonet short for chapel de bonet cap of some kind of material (med.L bonetus)
Useful english dictionary. 2012.