IPA: /ˈwɪndəʊsɪl/
KK: /ˈwɪndoʊsɪl/
The flat surface at the bottom of a window where you can place things.
She put the flower pot on the windowsill to get more sunlight.
Windowsill → It is formed from "window" (from Old Norse *vindauga*, meaning wind eye) and "sill" (from Old English *syll*, meaning a ledge or support). The word "windowsill" refers to the ledge or support at the bottom of a window.
Think of a 'window' as an 'eye' to the outside world, and the 'sill' as the 'ledge' that supports it. This helps you remember that a windowsill is the ledge at the bottom of a window.
No commonly confused words.