Demi is a prefix meaning "half", loaned from French; for example, demi frere which means "half brother" or demi soeur which means "half sister". Demi-glace is made by simmering and reducing by half a mixture of half brown stock and half espagnole sauce.
Demi also has Latin roots as a feminine given name, originally a nickname form of Demetria, the feminine form of the masculine name Demetrius, which is itself the Latin and English spelling of Greek name Demetrios.
- Demi Lovato (b. 1992), American actress and singer-songwriter
- Demi (author) (b. 1942), American children's book author
- Demi Delia (b. 1967), adult actress
- Demi Moore (b. 1962), American actress
- Demi Orimoloye (b. 1997), Canadian baseball player
- Demy (singer) (b. 1991), Greek singer