timidness vs self-doubt

timidness and self-doubt both are nouns.

Word	Noun	Adjective	Verb	Adverb
timidness	Yes	No	No	No
self-doubt	Yes	No	No	No

As nouns, self-doubt is a hyponym of timidness; that is, self-doubt is a word with a more specific, narrower meaning than timidness:

Other hyponyms of timidness include cold feet, shyness, diffidence, self-distrust.

timidness (noun)	self-doubt (noun)
fear of the unknown or unfamiliar or fear of making decisions	lack of self-confidence