forsake (v.)

[purpose], Middle English sake "strife, discord, enmity, dispute; legal dispute; blame, sin, guilt;" from Old English sacu "a cause at law, crime, dispute, guilt," from Proto-Germanic *sako "affair, thing, charge, accusation" (source also of Old Norse sök "charge, lawsuit, effect, cause," Old Frisian seke "strife, dispute, matter, thing," Dutch zaak "lawsuit, cause, sake, thing," German Sache "thing, matter, affair, cause"), from PIE root *sag- "to investigate, seek out" (source also of Old English secan, Gothic sokjan "to seek;" see seek).

Much of the word's original meaning has been taken over by case (n.1) and cause (n.), and it survives largely in phrases for the sake of and for _______'s sake "out of consideration or regard for" a person or thing (c. 1200, as for God's sake, early 14c.), both those formations are said to be probably from Norse, as their like has not been found in Old English.

mid-13c., past-participle adjective from forsake. Related: Forsakenly.