equinox

Where does the word "equinox" come from? It comes from Latin aequinoctium, and was adopted directly into English (1400s).

Equinox’s story begins in Latin: aequinoctium meant “equal night.” Literally equal night, from aequus (equal) and nox (night). It reached English by 1400s as equinox. Settled as the English word for the day of equal daylight and darkness. Today, equinox means either of the two times a year when day and night are of equal length.

1. Stage 1 · Latin · ancient aequinoctium "equal night", literally equal night, from aequus (equal) and nox (night).
2. Stage 2 · English · 1400s equinox "the time when day and night are of equal length", settled as the English word for the day of equal daylight and darkness.