expansion

(noun) the act of increasing (something) in size or volume or quantity or scope. Synonyms: enlargement.

(noun) a function expressed as a sum or product of terms. Example: "The expansion of (a+b)^2 is a^2 + 2ab + b^2."

(noun) a discussion that provides additional information. Synonyms: enlargement, elaboration.

(noun) adding information or detail. Synonyms: expanding upon.