AHA


Meaning of AHA in English

/ ɑːˈhɑː; NAmE / exclamation

used when you are expressing pleasure that you have understood sth or found sth out :

Aha! So that's where I left it!

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WORD ORIGIN

Middle English : from ah + ha (I).

Oxford Advanced Learner's English Dictionary.      Оксфордский английский словарь для изучающик язык на продвинутом уровне.