A half slip is a piece of lingerie that is worn underneath skirts and dresses. It begins at the waist and falls to the knee or lower but does not cover any portion of the torso. Half slips have three main purposes, to add a layer of fabric under a thin or see-through material, to help a skirt or dress fall properly on the body without sticking to a woman's legs, and to provide a layer of material between a coarse or rough material, such as wool, to protect the legs from irritation. Slips can be worn for any or all three of these reasons.
These pieces of lingerie are commonly made of nylon, cotton, tricot, silk, or a combination of any of these fabrics. Nylon is the most common material used because it does not cling or attach itself to clothing or the legs and is very good at preventing static cling. Slips usually have an elastic waist and an A-line style, though some can be more full and flowing than others. Unlike a full slip, a half slip does not cover a woman's upper body. If additional coverage is needed, a camisole can be worn with a half slip.
Half slips can be knee-length, for wearing under dresses and skirts that fall to the knee or below. They can also be mid-thigh length for wearing under shorter skirts or reach the ankles for use with formal dresses like wedding gowns. Each different style of half slip comes in several different lengths to accommodate women of different heights.
Neutral colors such as black, white, pink, and beige are the most common for half slips. These colors blend well with many different colors and materials and can be worn underneath a garment without being seen, even through a transparent material. Most slips are plain and without decoration to ensure that they remain unseen underneath the clothing and do not cause any ripples or wrinkles in the fabric of the skirt or dress. Some slips are edged in lace along the hemline for an added bit of design and to add a touch of femininity. Slips may also have a slit in the side, front or back so that they can be worn with clothing that has a slit in the skirt.
Petti-pants are similar to half slips, but where slips are designed like skirts, petti-pants are like a pair of loose fitting shorts. Both, however, are made of the same materials, come in the same colors, and are worn for the same reasons. Petti-pants can also be worn under pants or shorts, whereas a half slip cannot.