The noun is similarity.
The word 'noun' is not a verb. The word 'noun' is a noun, a word for a thing.
The noun form of the word "profess" is "profession."
The noun form of the adjective 'truthful' is truthfulness.The word 'truthful' is the adjective form of the noun truth.
The noun form of the word "resign" is "resignation."
The noun form for the word "proclaim" is "proclamation."
Similar is not a noun, it is an adjective, a word that describes a noun; for example similar outfits, similar tastes, similar backgrounds, etc.The noun form for the adjective similar is similarity.
The word debt does not have a verb form and is a noun. You can however use the word owe which is similar and is a verb.
The abstract noun form for the adjective similar is similarity.
The word 'noun' is not a verb. The word 'noun' is a noun, a word for a thing.
The noun form of the word "profess" is "profession."
The noun form of the adjective 'truthful' is truthfulness.The word 'truthful' is the adjective form of the noun truth.
The noun form for the adjective nervous is nervousness. Another noun form is nerve.
The noun form of the word "resign" is "resignation."
The noun form for the word "proclaim" is "proclamation."
The word substitute can be a verb and a noun. The verb form means to use something in place of something else. The noun form is a replacement for something which does a similar thing.
The noun form of the word "polite" is "politeness".
Protein is a noun. It is any of several complex chemicals used by living things.*The similar word is the adjective protean, which has the noun form proteanism.)