(h, h)  [a combination of the two interjections AH! and HA! formerly written separately, a ha. Cf. mod.Germ. aha! Fr. ah! ah!] 

    A. int. An exclamation expressing, with different intonations, surprise (arch. or obs.), triumph or satisfaction, and mockery or irony.
 
  c1386 CHAUCER Nun's Pr. T. 561 They crieden, out!.. A ha the fox! and after him thay ran. 1509 Parlyament of Deuylles xc, ‘A ha’ sayd Adam, ‘my God I se.’ 1611 BIBLE Is. xliv. 16 He warmeth himself, and saith, Aha, I am warm. Ps. xxxv. 21 Yea they opened their mouth wide against me, and saide, Aha, Aha, our eye hath seene it. 1861 C. READE Cloister & Hearth I. 344 Next will comeCramps of the Stomach. Aha! ThenBilious Vomit. Aha!
 

    B. n. Used attrib., as aha experience [tr. G. aha-erlebnis (K. Bühler (1908) in Arch. Ges. Psychol. XII. 18)], (the experience of) a moment of sudden insight or discovery; the sudden finding of a solution to a problem; also aha moment, reaction, etc.
 
  1939 L. E. COLE Gen. Psychol. 666 ‘Aha-moment’, the moment of insight. 1947 P. L. HARRIMAN Dict. Psychol. 18 ‘Ah-ah’ experience, the sudden achievement of insight... The catch-phrase..comes, of course, from the tale about Archimedes. 1951 D. RAPAPORT tr. K. Bühler in Organiz. & Pathol. Thought ii. 49 Then comprehension came suddenly with an affect like ‘Aha!’ (not spoken)... [Note] To my knowledge, this is the first mention of the often-quoted aha-phenomenon. 1962 Listener 20 Sept. 436/2 They [sc. computers] sometimes reach solutions suddenly, and they do this under circumstances in which human subjects are likely to have an ‘aha!’ experience. 1970 A. TOFFLER Future Shock xv. 300 At the level of ideas or cognition, this is the ‘a-hah!’ reaction we experience at a moment of revelation, when we finally understand something that has been puzzling us. 1980 Dædalus Spring 131 Those famous moments of inspiration, one-liners, and ‘Aha!’ experiences that creativity studies cite.