demi-

1. a combining form appearing in loanwords from French meaning “half” (demilune), “lesser” (demitasse), or sometimes used with a pejorative sense (demimonde); on this model, also prefixed to words of English origin (demigod).

prefix

1. halfdemirelief Compare hemi-, semi- (def. 1)
2. of less than full size, status, or rankdemigod

word-forming element meaning “half, half-sized, partial,” early 15c., from Old French demi “half” (12c.), from Late Latin dimedius, from Latin dimidius “half, one-half,” which contains the elements dis- “apart” (see dis-) + medius “middle” (see medial).

pref.

1. Half:demilune.