How many letters does the top answer for “of or relating to the chest or thorax” have?

The most common answer is pectoral (8 letters).

Crossword clue: of or relating to the chest or thorax

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

pectoral 8 letters wn-def

either of two large muscles of the chest

thoracic 8 letters wn-def

of or relating to the chest or thorax

relating to the abdomen and the thorax, or chest. 75% similar → abdominothoracic