jalousie

Jalousie is French: jalousie (jealousy), from Old French jalousie, from jalous (jealous), from Late Latin zelosus (full of zeal), from Greek zelos (zeal, jealousy). The window was named for jealousy because its angled slats allow the occupant to see out without being seen from outside — the position of the jealous person, watching without being caught watching.

Jalousie windows originated in the Mediterranean and became popular in tropical and subtropical architecture. The angled glass louvers (or sometimes wooden slats) can be tilted open to allow airflow while blocking direct rain and sun. In hot, humid climates — Florida, Hawaii, the Caribbean, Southeast Asia, Australia — jalousie windows were the standard before air conditioning. They provided constant ventilation.

The jalousie window fell from favor in the late twentieth century. The slats do not seal tightly, making the windows poor insulators and easy entry points for burglars. Air-conditioned buildings need sealed windows. Building codes in hurricane-prone areas restricted or banned jalousies because the glass slats shatter easily in high winds. The tropical window designed for tropical conditions was outlawed by tropical storms.

Jalousie windows survive in older buildings in Hawaii, Florida, and throughout the Caribbean. They are considered a distinctive architectural feature — charming in preservation, impractical in new construction. The word remains in English as a specific architectural term, though most English speakers do not recognize it. The jealousy window is itself barely visible.