A babydoll is a short nightgown or negligee intended as nightwear for a female. The garment is often trimmed with lace, ruffles, bows and ribbons, optionally with spaghetti straps. Sometimes it is made of sheer or translucent fabric like nylon or chiffon or silk.

It is said the name was popularized by the 1956 movie Baby Doll starring Carroll Baker in the title role, which essentially marked the beginning of the enduring popularity of the style for adults. At the same time, new synthetic fabrics and boutique retailing made the form both affordable and easy to purchase.

Short daywear dresses of a similar style are sometimes called babydoll dresses; the name is sometimes two words, baby doll, and sometimes hyphenated, baby-doll. Some styles are similar to what is worn by dolls in the form of infants, and by some infants; the gown is short enough that diapers are easily changed. Thus, it is a common garment for those who indulge in sexualized play-acting around ideas of infantilism. However, there may be an alternative origin for the style, if we consider the lineage of lace-trimmed shortie bed-jackets and bed-capes of the 1930s and 1940s.

It is now a highly eroticized item of adult apparel, often classified as a form of lingerie. When worn by an adult woman there is great contrast to when worn by an infant; the legs are fully displayed and some styles emphasize or deliberately expose the breasts as well. The gown is often sold as a set with panties as a typical babydoll is short enough that these are visible when it is worn with them. Styles of the same general length but not intended to emphasize sex appeal are sometimes called shortie nightgowns.

They are now available in a sufficiently wide variety of styles that many lingerie retailers consider babydolls a distinct department. Modern baby dolls often vary considerably from the styles of the 1960s and 70s. Baby doll negligees from the 1950s to the early 1980s are now collectable items.