How many letters does the top answer for “one of a set of parallel slats in a door or window to admit air and reject rain” have?

The most common answer is louver (6 letters).

Crossword clue: one of a set of parallel slats in a door or window to admit air and reject rain

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

louver 6 letters wn-def

one of a set of parallel slats in a door or window to admit air and reject rain

louvre 6 letters wn-def

one of a set of parallel slats in a door or window to admit air and reject rain