Extensive, a.
Etymology: [L. extensivus: cf. F. extensif. See Extend.]
1. Having wide extent; of much superficial extent; expanded; large; broad; wide; comprehensive; as, an extensive farm; an extensive lake; an extensive sphere of operations; extensive benevolence; extensive greatness.
2. Capable of being extended. [Obs.] Silver beaters choose the finest coin, as that which is most extensive under the hammer. Boyle.
Shades of meaning
Fernald has no entry of its own for extensive; he lists it under large.
He lists it without comment; the entries above explain its neighbors.