alone:  Although partly disguised by its pronunciation, alone is in fact simply a compound of all and one (whose /wun/ pronunciation began to develop around the 15th century). In Old English it was a completely separate phrase, all āna, literally ‘completely by oneself’, but by the 13th century this had coalesced into a single word. Loss of its initial ain the 14th century gave rise to the adjective lone. => all, lone, one
c. 1300 contraction of all ane, from Old English all ana "unaccompanied, all by oneself," from all "all, wholly" (see all) + an "one" (see one). Similar compounds are found in German (allein) and Dutch (alleen).