Why is the ninth month called September?
"purpose," Old English sacu "a cause at law, crime, dispute, guilt," from Proto-Germanic *sako "affair, thing, charge, accusation" (cf. 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" (cf. 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."