How many letters does the top answer for “marked by calm self-control (especially in trying circumstances); unemotional” have?

The most common answer is coolheaded (10 letters).

Crossword clue: marked by calm self-control (especially in trying circumstances); unemotional

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

coolheaded 10 letters wn-def

marked by calm self-control (especially in trying circumstances); unemotional

nerveless 9 letters wn-def

marked by calm self-control (especially in trying circumstances); unemotional