Merriam-Webster points out something I’d never noticed: In many languages, the word for night consists of the word for eight preceded by the letter N:

English: N + eight = Night
German: N + acht = Nacht
French: N + huit = Nuit
Spanish: N + ocho = Noche
Italian: N + otto = Notte
Portuguese: N + oito = Noite

It’s a coincidence. Romance languages derive their words for eight and night from the Latin octo and noctem, and the Germanic languages get them from the Old High German ahto and the Germanic naht. In each case the similarity of the sounds is just happenstance.

(Thanks, Sharon.)