A slip is a woman's undergarment worn beneath a dress or skirt to help it hang smoothly and to prevent chafing of the skin from coarse fabrics such as wool. Slips are also worn for warmth, and to protect fine fabrics from perspiration.

A full slip hangs from the shoulders, usually by means of narrow straps, and extends from the breast to the fashionable skirt length.

A half slip hangs from the waist. May also be called a waist slip or rarely a petticoat.

Slips are usually made of a smooth and slippery fabric such as silk, satin, polyester, tricot or nylon, although cotton slips are also used particularly in hot countries. They are often decorated with lace at the edges and hem, and are typically worn over more intimate undergarments. Slips are also worn for modesty under translucent outer garments. A half slip may be worn with a matching camisole as an alternative to a full slip.

A slip dress is a dress for street wear styled like a slip, fitting close to the body and having narrow shoulder straps.

The term should not be confused with the British English ”gymslip,” an outer garment worn by girls during physical education classes in high school.

In various other languages, such as Dutch, French, German and Greek, ”slip” refers to different types of undergarment: tightly fitting, both male and female undershorts, such as briefs and thongs.