bonnet vs cowl

bonnet and cowl both are nouns.

Word	Noun	Adjective	Verb	Adverb
bonnet	Yes	No	Yes	No
cowl	Yes	No	Yes	No

As nouns, bonnet and cowl are synonyms defined as:

bonnet and cowl: protective covering consisting of a metal part that covers the engine

Other synonyms of bonnet include cowling, hood.

bonnet (noun)	cowl (noun)
a hat tied under the chin	protective covering consisting of a metal part that covers the engine
protective covering consisting of a metal part that covers the engine	a loose hood or hooded robe (as worn by a monk)

bonnet (verb)	cowl (verb)
dress in a bonnet	cover with or as with a cowl