> a /ə/, prep.1
Also o.
Etymology: A worn-down proclitic form of OE. preposition an, on. In compounds and common phrases this became a even in OE., as abútan, a timan. The separate an was labialized to on, which form also (in West Saxon) absorbed the prep. in, and so had the meanings on, in; unto, into, to. In 11th c., on began to be reduced before consonants to o, which from its tonelessness soon sank to a /ə/. Before a vowel an was occasionally used; when emphatic on remained. The separate a is now rarely used, being replaced by the full on, in, or the various prepositions which represe…