"purpose," Old English sacu "a cause at law, crime, dispute, guilt," from Proto-Germanic *sako "affair, thing, charge, accusation" (cognates: 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" (cognates: Old English secan, Gothic sokjan "to seek;" see seek).Much of the word's original meaning has been taken over by case, n.1, cause, n., and it survives largely in phrases for the sake of (early 13c.) and for _______'s sake (c.1300, originally for God's sake), both probably are from Norse, as these forms have not been found in Old English.

"Japanese rice liquor," 1680s, from Japanese sake, literally "alcohol."