IPA: /ˈklaʊlɪt/
KK: /ˈklaʊlɪt/
A small cloud or something that looks like a cloud.
The sky was filled with fluffy cloudlets drifting by.
Cloudlet is formed from "cloud" (from Old English "clud", meaning a mass of rock or hill, which evolved to mean a visible mass of condensed water vapor in the sky) and the diminutive suffix "-let" (meaning small). The word "cloudlet" refers to a small cloud.
Think of a 'cloud' as a mass of vapor in the sky, and the '-let' means small, so a cloudlet is simply a small cloud.