Word Study
Aha
CIDE DICTIONARY
Aha, interj. [Ah, interj. + ha.].
An exclamation expressing, by different intonations, triumph, mixed with derision or irony, or simple surprise. [1913 Webster]
Aha, n.
A sunk fence. See Ha-ha. Mason. [1913 Webster]
OXFORD DICTIONARY
Aha, int. expressing surprise, triumph, mockery, irony, etc.
Usage
The sense depends much on intonation.
Etymology
ME f. AH + HA
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