crookback vs humpbacked

crookback is a noun but humpbacked is not a noun.

Word	Noun	Adjective	Verb	Adverb
crookback	Yes	Yes	No	No
humpbacked	No	Yes	No	No

As adjectives, crookback and humpbacked are synonyms defined as:

crookback and humpbacked: characteristic of or suffering from kyphosis, an abnormality of the vertebral column

Other synonyms of crookback include crookbacked, gibbous, humped, hunchbacked, kyphotic.

crookback (noun)	humpbacked (noun)
a person whose back is hunched because of abnormal curvature of the upper spine

crookback (adjective)	humpbacked (adjective)
characteristic of or suffering from kyphosis, an abnormality of the vertebral column	characteristic of or suffering from kyphosis, an abnormality of the vertebral column