1. windowsill
Your windowsill is so dirty, I could confuse it with a pigsty.
There's a crack in the windowsill
Put this plant on the windowsill.
Where are the book and pencil? The book's on the table, and the pencil's on the windowsill.
English word "un rebord de fenêtre"(windowsill) occurs in sets:
Furniture and furnishings