From WordNet (r) 2.0 (August 2003) [wn]:
massive
adj 1: imposing in size or bulk or solidity; "massive oak doors";
"Moore's massive sculptures"; "the monolithic
proportions of Stalinist architecture"; "a monumental
scale" [syn: monolithic, monumental]
2: being the same substance throughout; "massive silver"
3: imposing in scale or scope or degree or power; "massive
retaliatory power"; "a massive increase in oil prices";
"massive changes"
4: consisting of great mass; containing a great quantity of
matter; "Earth is the most massive of the terrestrial
planets"
From The Collaborative International Dictionary of English v.0.48 [gcide]:
massive \mass"ive\ (m[.a]s"[i^]v), a. [F. massif.]
1. Forming, or consisting of, a large mass; compacted;
weighty; heavy; massy. "Massive armor." --Dr. H. More.
[1913 Webster]
2. (Min.) In mass; not necessarily without a crystalline
structure, but having no regular form; as, a mineral
occurs massive.
[1913 Webster]
Massive rock (Geol.), a compact crystalline rock not
distinctly schistose, as granite; also, with some authors,
an eruptive rock.
[1913 Webster]