Bonnet has been used as the name for a wide variety of headgear for both sexes—more often female—from the Middle Ages to the present. As with "hat" and "cap", it is impossible to generalize as to the styles for which the word has been used, but there is for both sexes a tendency to use the word for styles in soft material and lacking a brim, or at least one all the way round, rather than just at the front. Yet the term has also been used, for example, for steel helmets. This was from Scotland (in 1505), where the term has long been especially popular.
Headgear tied under the chin with a string was especially likely to be called a bonnet. Other features associated with bonnets as opposed to hats was that the forehead was not covered, and the back of the head often was. The headgear of female servants and workers was more likely to be called a bonnet. In summary, hats were often stiffer, worn on the top of the head with the crown and brim roughly horizontal, while bonnets were pushed back, covering the back of the head, with any brim often approaching the vertical at the front. Other types of bonnet might otherwise be called "caps", for example the Scottish blue bonnet worn by working-class men and women, a kind of large floppy beret.
Bonnet derives from the same word in French, where it originally indicated a type of material. From the 18th century bonnet forms of headgear, previously mostly only worn by elite women in informal contexts at home, became adopted by high fashion, and until at least the late 19th century, bonnet was the dominant term used for female hats. In the 21st century, only a few kinds of headgear are still called bonnets, most commonly those worn by babies and Scottish soldiers. In addition, types of headgear called bonnets are worn by women as a Christian headcovering in some denominations such as Anabaptists and Conservative Quakers, mainly in America.
Until the late 19th century bonnet seems to have been the preferred term for most types of hats worn by women, while "hat" was more reserved for male headgear, and female styles that resembled them, typically either in much smaller versions perched on top of the head, or versions with very wide brims all the way round. In the mid-17th and 18th century house bonnets worn by women and girls were generally brimless headcoverings which were secured by tying under the chin, and which covered no part of the forehead. They were worn indoors, to keep the hair tidy, and outdoors, to keep dust out of the hair. With hairstyles becoming increasingly elaborate after 1770, the calash was worn outdoors to protect the hair from wind and weather: a hood of silk stiffened with whalebone or arched cane battens, collapsible like a fan or the calash top of a carriage, they were fitted with ribbons to allow them to be held secure in a gale.
From Waterloo, more structured fashionable bonnets made by milliners rapidly grew larger. A plate in La Belle Assemblée 1817 showed a
Bonnet of vermillion-coloured satin, embossed with straw, ornamented slightly with straw-coloured ribbands, and surmounted by a bouquet formed of a full blown damask rose and buds, with ears of ripe corn. This ornament is partially placed on one side: the edge of the bonnet finished by blond [lace] laid on strait.
This was specified as a carriage dress, with the understanding that when taking the air in an open carriage, the bonnet provided some privacy—such a bonnet was in fact an invisible in Paris—and prevent wind-chapping, with its connotations of countrified rude health. Straw was available again after 1815: the best straw bonnets came from Leghorn. As a bonnet developed a peak, it would extend from the entire front of the bonnet, from the chin over the forehead and down the other side of the face. Some styles of bonnets between ca 1817 and 1845 had a large peak which effectively prevented women from looking right or left without turning their heads: a "coal-scuttle" or "poke" bonnet. Others had a wide peak which was angled out to frame the face. In the 1840s it might be crimped at the top to frame the face in a heart shape. As the bonnet became more complicated, under it might be worn a lace cornette to hold the hair in place.
The lack of a clear distinction between hats and bonnets can be seen in these extracts from Harper's Bazaar in 1874: (On "Paris Fashions", by Emmeline Raymond, 11 April) "There is no change in bonnets. So long as the hair is piled on top of the head, the little device which takes the place of a dress cap must remain as it is. The brims are generally flattened at the sides, swelling above the front, and turned up behind in order to make room for the hair, which would not find room whereon to lodge if the precaution were not taken, here and there, to punch out what is called a brim of what is called a bonnet. It is said, however, that straw hats of the Pamela shape are in preparation, that is, turned up behind, but shading the forehead. It would be so sensible to wear a bonnet that would protect the face from the sun that I give this news with due caution. For my part, I can not believe it." A week before, ("New York Fashions", 4 April): "Strings are seldom seen, and this does away with the last distinguishing feature between bonnets and round hats; the same head-covering now serves for each, as it is a bonnet when worn far back on the head, and a hat when tilted forward."
Bonnets remained one of the most common types of headgear worn by women throughout most of the 19th century. For a widow, a bonnet was de rigueur. Silk bonnets, elaborately pleated and ruched, were worn outdoors, or in public places like shops, galleries, churches, and during visits to acquaintances. The idea was that women would cover their heads with caps out of modesty. In addition, women in wedlock would wear caps and bonnets during the day.
Many Anabaptist women wear bonnets due to religious beliefs.
Under the French Second Empire, parasols took the place of protection from sun, and bonnets became smaller and smaller, until they could only be held on the head with hatpins. As hats came back into style, bonnets were increasingly worn by women who wanted to appear modest in public, with the result that bonnets accumulated connotations of dowager wear and dropped from fashion except on the prairies.
Most middle-class women in the 19th century would have had at least two bonnets, one suitable for summer weather, often made from straw, and one made from heavier fabric for winter wear. This is where the tradition of an Easter bonnet originated, when women would switch from their winter bonnet to their summer bonnet. Wealthier women would have many bonnets, suitable for different occasions.
Women of some religious groups have continued to wear bonnets for worship or everyday clothing. This is especially the case among plain people, such as plain-dressing Friends (Quakers), Old Order Mennonites and the Amish. Bonnets were adopted by the Salvation Army as part of uniform regalia for women. Initially, Salvation Army bonnets were introduced as protection for women soldiers and were reinforced with black tar to turn them into helmets. Later versions were smaller when there was no longer any need for protection. The bonnet has now been replaced with a bowler hat.
In France, single women wear elaborate yellow and green bonnets to honor St. Catherine's Day on November 25. The French expression coiffer Sainte-Catherine ('don St. Catherine's bonnet'), an idiom that describes an unmarried woman of 25 years or older, derives from this custom.
Slave woman shipped over from Africa, traditionally wore African head dress in their native countries were forced to adapt European bonnets from their captor traditional wardrobe.Since slaves were expected to perform working task they were often given bonnets of a traditional european maid style. While slaves in the yard wore hand tied bonnets made from nappy similar to the nappy cloths used for baby diapers. These head bonnets were prefered by the masters for hygiene and to hide unkept slave hair while also offering protection from the sun. 
The word bonnet for male headgear was generally replaced in English by cap before 1700, except in Scotland, where bonnet and the Scots language version bunnet remained in use, originally for the widely worn blue bonnet, and now especially for military headgear, like the feather bonnet (not to be confused with those worn by Native Americans, for which bonnet was also used), Glengarry, Kilmarnock and Balmoral. The Tudor bonnet remains a term for a component of the academic regalia of some universities, and is not unlike the common male bonnet of the 16th century.
Bonnet is also the term for the puffy velvet fabric inside the coronet of some male ranks of nobility, and "the affair of the bonnets" was a furious controversy in the France of Louis XIV over the mutual courtesies due between the magistrates of the Parlement de Paris and the Dukes of France.
The Scotch bonnet pepper was named for its resemblance to a bonnet worn by men in Scotland in the past, as it had a pom pom at the top which indicates the difference form the men's bonnet and women's bonnet.
Various tam o' shanters
The most common kind of bonnet worn today is a soft headcovering for babies. Its shape is similar to that of some kinds of bonnets that women used to wear: it covers the hair and ears, but not the forehead.
Grand Duchess Tatiana Nikolaevna of Russia in 1898 in a grand bonnet
Bonnets in the 2000's are highly stylish and valued in the African American community. A traditional head dressing for sleeping, it is a protective style preserver. This is a tradition passed down from the bonnet adaptation during slavery which faded away in other cultures. Modern bonnets are often made of silk or satin and maintain a similar shape to bonnets that were popular during the nineteen sixties.
- de Courtais, 102, 110
- OED, "Bonnet"
- de Courtais, 102
- Bercot, David (2017). "Head Covering Through the Centuries". Scroll Publishing. Retrieved 11 May 2017.
- Both quoted in "Is it a hat? or maybe it’s a bonnet ...?", Living History Farms blog, 7 September 2015
- Wass, Ann, and Michelle Fandrich. Clothing through American History: The Federal Era through Antebellum, 1786-1860. Library of Congress Cataloging-in-Publication Data, 2010.
- Bender, Harold S. and Sam Steiner. "Bonnet (1953) Archived December 12, 2007, at the Wayback Machine." Global Anabaptist Mennonite Encyclopedia Online. 2000. Global Anabaptist Mennonite Encyclopedia Online. Retrieved 2007-04-27.
- "Coiffer sainte Catherine". La France pittoresque (in French). November 24, 2016.
- . july 25, 2019 [www.blackwoman.com www.blackwoman.com] Check
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- OED, "Bonnet" 4