expression of surprise or delighted discovery, late 14c., from ah + ha.
This seely widewe and hire doughtres two ... cryden out "harrow!" and "weloway! A ha! þe fox!" and after him they ran [Chaucer]
*agro-
agronomy
aground
ague
ah
aha
a-ha
ahead
ahem
ahimsa
ahistoric
)window.location='https://www.paypal.com/cgi-bin/webscr?cmd=_donations&business=byronic106@yahoo.com&lc=US&item_name=Donation+to +Help+Keep+Etymonline+Free+and+Open&no_note=0&cn=&curency_code=USD&bn=PP-DonationsBF:btn_donateCC_LG.gif:NonHosted'){kind=link}