IPA: /ˈwɪndləs/
KK: /ˈwɪndləs/
Having no wind; a calm condition without any breeze.
The lake was perfectly still on the windless day.
Windless → It is formed from "wind" (from Old English "wind", meaning air in motion) and "-less" (meaning without). The word "windless" describes a state of having no wind or being without air movement.
Think of being 'without' ('-less') any 'air in motion' ('wind') — that's what windless means.