for-

1.
a prefix meaning “away,” “off,” “to the uttermost,” “extremely,” “wrongly,” or imparting a negative or privative force, occurring in verbs and nouns formed from verbs of Old or Middle English origin, many of which are now obsolete or archaic:
forbid; forbear; forswear; forbearance.
Origin
Middle English, Old English; compare German ver-, Greek peri-, Latin per-
British Dictionary definitions for for-

for-

prefix
1.
indicating rejection or prohibition: forbear, forbid
2.
indicating falsity or wrongness: forswear
3.
used to give intensive force: forgive, forlorn
Word Origin
Old English for-; related to German ver-, Latin per-, Greek peri-
Word Origin and History for for-

prefix usually meaning "away, opposite, completely," from Old English for-, indicating loss or destruction, or completion, also used as an intensive or pejorative element, which is related to Old Norse for-, Dutch ver-, Old High German fir-, German ver-; from PIE *pr-, from root *per- (1) "forward, through" (see per). Probably originally in Germanic with a sense of "forward, forth," but with complex sense developments in the various languages. Ultimately from the same root as fore (adv.).