1640s, from Latin praefixum, noun use of neuter past participle of praefigere "fix in front, fasten on before," from prae "before" (see pre-) + root of figere "to fasten, fix" (see fix, v.).

early 15c., "appoint beforehand," from Middle French prefixer, from pre- (see pre-) + fixer (see fix, v.). Meaning "to place at the beginning" is from 1530s; of words or parts of words from c.1600. Related: Prefixed; prefixing.