How many letters does the top answer for “weak or sickly person especially one morbidly concerned with his or her health” have?

The most common answer is valetudinarian (14 letters).

Crossword clue: weak or sickly person especially one morbidly concerned with his or her health

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

valetudinarian 14 letters wn-def

weak or sickly person especially one morbidly concerned with his or her health