आ-

Borrowed from Sanskrit आ- (ā-), from Proto-Indo-Iranian *HáH, from Proto-Indo-European *h₂éd (“to, at”). Distant cognate with English at and Latin ad- (whence French a-).

• (Delhi) IPA^(key): /ɑː/, [äː]

आ- • (ā-)

1. (no longer productive) a prefix found in many Sanskrit learned borrowings, meaning "towards", "near", or "up to"; ad-, in-

   ‎आ- (ā-) + ‎प्रवास (pravās, “migration, emigration”) → ‎आप्रवास (āpravās, “immigration”)

2. up to, as far as, until

   ‎आ- (ā-) + ‎जीवन (jīvan, “life”) → ‎आजीवन (ājīvan, “for life, lifelong”)

• McGregor, Ronald Stuart (1993) “आ-”, in The Oxford Hindi-English Dictionary, London: Oxford University Press

From the postposition/preposition आ (ā́).

• (Vedic) IPA^(key): /ɑ́ː/
• (Classical Sanskrit) IPA^(key): /ɑː/

आ- • (ā́-)

1. ad-
2. implies diminution when prefixed to adjectives

   ‎आ- (ā-) + ‎नील (nīla, “dark”) → ‎आनील (ānīla, “darkish”)

• Monier Williams (1899) “आ-”, in A Sanskrit–English Dictionary, […], new edition, Oxford: At the Clarendon Press, →OCLC, page 126, columns 1-2.
• Mayrhofer, Manfred (1992) “ā́”, in Etymologisches Wörterbuch des Altindoarischen [Etymological Dictionary of Old Indo-Aryan]‎^[1] (in German), volume 1, Heidelberg: Carl Winter Universitätsverlag, pages 157-8