Noun

1. A component in a ventilation system.
2. Upward sloping window slats which form a blind or shutter, allowing light and air in but excluding rain and direct sun.

   “A small lofty room, with its window wide open, and the wooden jalousie-blinds closed, so that the dark night only showed in slight horizontal lines of black, alternating with their broad lines of stone colour.” — Dickens, Tale of Two Cities

Etymology

1. From < < .

Noun

1. jealousy
2. System to shade a window, like a curtain, but hanging from the ceiling and one can control how much light passes through.