gloom vs apprehensiveness

gloom and apprehensiveness both are nouns.

Word	Noun	Adjective	Verb	Adverb
gloom	Yes	No	No	No
apprehensiveness	Yes	No	No	No

As nouns, apprehensiveness is a hypernym of gloom; that is, apprehensiveness is a word with a broader meaning than gloom:

Other hypernyms of gloom include apprehension, dread, melancholy.

gloom (noun)	apprehensiveness (noun)
a feeling of melancholy apprehension	fearful expectation or anticipation
a state of partial or total darkness
an atmosphere of depression and melancholy