1 large and heavy or solid.
2 (of the features, head, etc.) relatively large; of solid build.
3 exceptionally large (took a massive overdose).
4 substantial, impressive (a massive reputation).
5 Mineral. not visibly crystalline.
6 Geol. without structural divisions.
Derivatives:
massively adv. massiveness n.
Etymology: ME f. F massif -ive f. OF massiz ult. f. L massa MASS(1)
Useful english dictionary. 2012.