- [OE] The word ant appears to carry the etymological sense ‘creature that cuts off or bites off’. Its Old English form, æmette, was derived from a hypothetical Germanic compound *aimaitjōn, formed from the prefix *ai- ‘off, away’ and the root *mait- ‘cut’ (modern German has the verb meissen ‘chisel, carve’): thus, ‘the biter’. The Old English word later developed along two distinct strands: in one, it became emmet, which survived into the 20th century as a dialectal form; while in the other it progressed through amete and ampte to modern English ant. If the notion of ‘biting’ in the naming of the ant is restricted to the Germanic languages (German has ameise), the observation that it and its nest smell of urine has been brought into play far more widely. The Indo-European root *meigh-, from which ultimately we get micturate ‘urinate’ , was also the source of several words for ‘ant’, including Greek múrmēx (origin of English myrmecology ‘study of ants’, and also perhaps of myrmidon  ‘faithful follower’, from the Myrmidons, a legendary Greek people who loyally followed their king Achilles in the Trojan war, and who were said originally to have been created from ants), Latin formīca (hence English formic acid , produced by ants, and formaldehyde ), and Danish myre. It also produced Middle English mire ‘ant’, the underlying meaning of which was subsequently reinforced by the addition of piss to give pismire, which again survived dialectally into the 20th century.
The Hutchinson dictionary of word origins. 2013.