'jalousie' originates from French, specifically the word 'jalousie', which itself comes from Italian 'gelosia', where the root 'gelos-' meant 'jealousy' or 'zeal'.

'jalousie' changed from the French word 'jalousie' meaning 'jealousy' and, by extension in English usage from the 18th–19th century, came to refer to a 'louvered shutter or blind' (perhaps from the idea of screening or hiding); it eventually became the English noun 'jalousie' for the slatted window/blind.

Initially it meant 'jealousy' (an emotion), but over time in English it evolved into the additional meaning 'louvered window or blind' (a screened or slatted window covering).