impairment vs bow legs

impairment and bow legs both are nouns.

Word	Noun	Adjective	Verb	Adverb
impairment	Yes	No	No	No
bow legs	Yes	No	No	No

As nouns, bow legs is a hyponym of impairment; that is, bow legs is a word with a more specific, narrower meaning than impairment:

impairment: the condition of being unable to perform as a consequence of physical or mental unfitness
bow legs: outward curvature of the legs

impairment (noun)	bow legs (noun)
damage that results in a reduction of strength or quality	outward curvature of the legs
the act of making something futile and useless (as by routine)
the occurrence of a change for the worse
the condition of being unable to perform as a consequence of physical or mental unfitness
a symptom of reduced quality or strength