It is a cuter name for underwear. There are men that call their underwear panties.
Female underwear are called panties because at one time they were called pantaloons.
Why are panties called panties. The first use of the word panties was recorded in 1908. The reason theyre called a pair of panties even today is that they used to be a literal pair of two legs that joined together in the middle. People started calling drawers panties in the 20th century.
They are worn by children and women but also men. So the name just was shortened to panties.