(transitive) To form or collect into a mass; to form into a collective body; to bring together into masses; to assemble. (intransitive) To have a certain mass.

Is massive a noun or a verb?

MASSIVE (noun) definition and synonyms | Macmillan Dictionary.

Is massive a adverb?

In a massive manner, in a way that appears large, heavy or imposing. (slang) Greatly.