Bonnet is a term for a wide variety of styles of headgear for both sexes, but most often female, which has been in use from the Middle Ages to the present. It is impossible to generalize as to the styles for which the word has been used, any more than for the alternatives of hat or cap, but there is for both sexes a tendency to use the word for styles in soft material and lacking a brim. However 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.Bonnet derives from the same word in French, where it originally indicated a type of material. In the 21st century, only a few kinds of headgear are still referred to as bonnets, most commonly those worn by babies and Scottish soldiers.
The most common kind of bonnet worn today is a soft headcovering for babies. They are shaped similarly to the kind of bonnets women used to wear, that is they cover the hair and ears, but not the forehead. See also Coif.
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.