*oi-no-

indefinite article, the form of an used before consonants, mid-12c., a weakened form of Old English an "one" (see an). The disappearance of the -n- before consonants was mostly complete by mid-14c. After c. 1600 the -n- also began to vanish before words beginning with a sounded -h-; it still is retained by many writers before unaccented syllables in h- or (e)u- but is now no longer normally spoken as such. The -n- also lingered (especially in southern England dialect) before -w- and -y- through 15c.

It also is used before nouns of singular number and a few plural nouns when few or great many is interposed.

"unaccompanied, solitary; without companions," c. 1300, a contraction of all ane, from Old English all ana "unaccompanied, all by oneself," literally "wholly oneself," from all "all, wholly" (see all) + an "one" (see one). It preserves the old pronunciation of one.

Similar compounds are found in German (allein) and Dutch (alleen). The sense of "and nothing else" is from c. 1200, as in "Man does not live by bread alone" (Matthew iv.4, KJV; there Tyndale has "man shall not lyve by brede onlye"). Related: Aloneness. Adverbial alonely seems to have become obsolete 17c.