Panties

Panties are a kind of underwear. Women's panties are also called knickers. Other names are underpants ("undies"), briefs and smalls.
There are many different shapes and sizes of panties. A common type are bikini panties, which are usually small like a bikini bottom. Bloomers are panties which are loose-fitting and bigger. Panties with a high waistline are usually thought to be worn by older or more conservative women. 
Panties may be made of silk, cotton, satin or man-made fabrics, and decorated with lace. Most full cut panties are made of cotton or other comfortable materials.
Names.
Knickers in British English only refers to female panties; in American usage the term is also used for a type of male trousers more properly called "breeches".