ionsaitheacht

== Irish == === Etymology === From ionsaigh (“advance upon, attack; proceed to, approach; set about, attempt; reach, attain; seek out”) +‎ -acht (abstract nominal suffix). === Noun === ionsaitheacht f (genitive singular ionsaitheachta) (optics) incidence ==== Declension ==== ==== Related terms ==== ionsaitheach (“incident”, adjective) === Mutation === === Further reading === Ó Dónaill, Niall (1977), “ionsaitheacht”, in Foclóir Gaeilge–Béarla, Dublin: An Gúm, →ISBN