IPA: /ˈnaɪtˌfɔl/
KK: /naɪtˌfɔl/
The time when it becomes dark in the evening, marking the end of the day.
As nightfall approached, the stars began to twinkle in the sky.
Nightfall → It is formed from "night" (from Old English "niht", meaning the period of darkness) and "fall" (from Old English "feallan", meaning to fall or descend). The word "nightfall" describes the time when night descends or falls upon the day.
Think of the 'darkness' of 'night' coming to 'fall' or descend, which helps you remember that nightfall is the time when night begins.
No commonly confused words.