Always
Middle English: genitive case of all way, the inflection probably giving the sense ‘at every time’ as opposed to ‘at one uninterrupted time’: the difference between the two is no longer distinct.
wiktionary
From Middle English alwayes, allwayes, allweyes, a variant of Middle English allwaye, alwey, alle wey(“always”), from Old English ealneġ, ealneweġ(“always, perpetually”, literally “all the way, all the while, continuously”), from ealne + weġ(accusative case), equivalent to alway + -s. Cognate with Scots alwayis(“always”), Low German allerwegens(“very often”, literally “all ways'”). More at all, way.
etymonline
always (adv.)
mid-14c., contraction of Old English phrase ealne weg "all the time; quite, perpetually," literally "all the way," with accusative of space or distance, though the oldest recorded usages refer to time; see all + way (n.). The adverbial genitive -s appeared early 13c., was rare before c. 1400, but is now standard, though the variant alway survived into 1800s. Meaning "every time" is from early 13c.
