How many letters does the top answer for “not provided with vents” have?

The most common answer is unvented (8 letters).

Crossword clue: not provided with vents

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

unvented 8 letters wn-def

not provided with vents

not equipped or provided 50% similar → unendowed

not provided with a frame 50% similar → unframed

not provided with curtains 50% similar → curtainless, uncurtained