How many letters does the top answer for “having a humped back.” have?

The most common answer is humpbacked (10 letters).

Crossword clue: having a humped back.

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

humpbacked 10 letters web-def

characteristic of or suffering from kyphosis, an abnormality of the vertebral column

hunchbacked 11 letters web-def

characteristic of or suffering from kyphosis, an abnormality of the vertebral column

having a hump, as the back. 50% similar → humped