IPA: /ˈsʌnˌdaʊn/
KK: /ˈsʌnˌdaʊn/
The time in the evening when the sun goes down and it becomes dark.
We watched the beautiful colors in the sky at sundown.
Sundown is formed from "sun" (from Old English "sunne", meaning the star that provides light and warmth) and "down" (from Old English "dūn", meaning a hill or mound, but in this context, it refers to the setting or lowering). The word "sundown" describes the time when the sun sets or goes down below the horizon.
Think of the 'sun' going 'down' as it sets in the evening — that's what sundown means.