alone: [13] 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[alone etymology, alone origin, 英语词源]