How many letters does the top answer for “not having a smile.” have?

The most common answer is smileless (9 letters).

Crossword clue: not having a smile.

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

smileless 9 letters web-def

Not having a smile.

not having a coating 50% similar → uncoated

not having a cord 50% similar → cordless

not having a duct 50% similar → ductless

not having a job 50% similar → jobless

not having a leg. 50% similar → legless

not having a tail 50% similar → anurous, tailless