"Day and night."
Translation:Latha agus oidhche.
a-nochd tonight indeed comes from a phrase meaning in night or the night, Old Irish innocht, from nocht night – but nocht had already been a very archaic word in OIr. that had been generally replaced and remained only in the petrified phrase innocht; the default word for night is oidhche from OIr. adaig, acc., dat. aidchi, gen. aidchi.