The term chemise or shift can refer to the classic smock, or else can refer to certain modern types of women's undergarments and dresses. In the classical usage it is a simple garment worn next to the skin to protect clothing from sweat and body oils, the precursor to the modern shirts commonly worn in Western nations.
Chemise is a French term (which today simply means shirt). This is a cognate of the Italian word camicia, and the Spanish / Portuguese language word camisa (subsequently borrowed as kameez by Hindi / Urdu / Hindustani), all deriving ultimately from the Latin camisia, itself coming from Celtic. (The Romans avidly imported cloth and clothes from the Celts.) The English called the same shirt a smock and the Irish called it a léine (Irish pronunciation: [l̠ʲeːnʲə]). For an alternative etymology from Persian via Arabic and ultimately Greek, rather than Latin roots, refer entry under Kameez.
In modern usage, a chemise is generally a woman's garment that vaguely resembles the older shirts but is typically more delicate, and usually provocative. Most commonly the term refers to a loose-fitting, sleeveless undergarment or type of lingerie which is unfitted at the waist. It can also refer to a short, sleeveless dress that hangs straight from the shoulders and fits loosely at the waist. A chemise typically does not have any buttons or other fasteners and is put on by either dropping it over the head or stepping into it and lifting it up.