worthlessness vs ineptitude

worthlessness and ineptitude both are nouns.

Word	Noun	Adjective	Verb	Adverb
worthlessness	Yes	No	No	No
ineptitude	Yes	No	No	No

As nouns, worthlessness and ineptitude are synonyms defined as:

worthlessness and ineptitude: having no qualities that would render it valuable or useful

worthlessness (noun)	ineptitude (noun)
having no qualities that would render it valuable or useful	having no qualities that would render it valuable or useful
the quality of being without practical use	unskillfulness resulting from a lack of training