bonnet

bonnet /ˈbɑːnət/ noun
plural bonnets
bonnet
/ˈbɑːnət/
noun
plural bonnets
Britannica Dictionary definition of BONNET
[count]
1 
: a hat that ties under the chin
◊ Bonnets were worn by women in the past but are now only worn by babies.
2 
British : 1hood 2b

have a bee in your bonnet

— see 1bee