How many letters does the top answer for “the state of being covered with dust” have?

The most common answer is dustiness (9 letters).

Crossword clue: the state of being covered with dust

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

dustiness 9 letters wn-def

the state of being covered with dust

the state of being covered with unclean things 50% similar → grime, grunge, soil