slenderness vs inadequacy

slenderness and inadequacy both are nouns.

Word	Noun	Adjective	Verb	Adverb
slenderness	Yes	No	No	No
inadequacy	Yes	No	No	No

As nouns, inadequacy is a hypernym of slenderness; that is, inadequacy is a word with a broader meaning than slenderness:

Other hypernyms of slenderness include deficiency, insufficiency.

slenderness (noun)	inadequacy (noun)
the quality of being slight or inadequate	unsatisfactoriness by virtue of being inadequate
the property of an attractively thin person	lack of an adequate quantity or number
relatively small dimension through an object as opposed to its length or width	a lack of competence