What does "blue bonnet" mean?

A traditional flat Scottish hat made of blue wool; a blue tam-o'-shanter.

What is a synonym for "blue bonnet"?

Common synonyms include: bluebonnet.

Pronounced //ˈbluː ˌbɒnɪt//.

/ˈbluː ˌbɒnɪt/ noun

noun ·Rare ·Advanced level

Noun

1
A traditional flat Scottish hat made of blue wool; a blue tam-o'-shanter.
"The blue bonnet, a national badge, is disappearing rapidly."
2
Someone who wears such a hat; a Scotsman, especially a Scottish soldier.
"Rob soon gathered an unco band o' blue-bonnets at his back."
3
Any of several blue flowering plants, especially cornflower, Centaurea cyanus, and plants of the genus Scabiosa.
4
A blue Australian parrot, especially Northiella haematogaster.
"And when he at last succeeds in trapping a one-guinea blue bonnet he can sit happily for hours marvelling at the beauty of its feathers, the rich blue around its parrot's beak, the yellow of its lower breast in which lovely sea you find a soft-edged island of rich blood red."
5
Any of several North American species of Lupinus common in the southwestern US, especially Lupinus texensis and Lupinus subcarnosus. US, especially

"The blue bonnet, a national badge, is disappearing rapidly."