What is the noun form of complment?

Answer 1

There is no word in English spelled 'complment'. This makes it difficult to know if you are asking about the noun complement or the noun compliment; they are both nouns which have different meanings.

The noun complement is a singular, common, abstract noun; a word for something that is added to something else; something that combines well with something else; a number or quantity of something required to make a group complete.

The noun compliment is a singular, common, abstract noun; a word for an expression of respect, affection, or admiration; an admiring remark; praise.

Answer 2

The noun form of "complement" is "complementarity."