Source : Webster's Revised Unabridged Dictionary (1913)

Ah \Ah\, interj. [OE. a: cf. OF. a, F. ah, L. ah, Gr. ?, Sk.
   [=a], Icel. [ae], OHG. [=a], Lith. ['a], ['a]['a].]
   An exclamation, expressive of surprise, pity, complaint,
   entreaty, contempt, threatening, delight, triumph, etc.,
   according to the manner of utterance.