mid-15c., "to make shorter," from Latin abbreviatus, past participle of abbreviare "to shorten, make brief," from ad "to" (see ad-) + breviare "shorten," from brevis "short, low, little, shallow" (from PIE root *mregh-u- "short").
Specifically of words by 1580s. Also sometimes 15c. abbrevy, from French abrevier (14c.), from Latin abbreviare. Related: Abbreviated; abbreviating.