(1):

(a.) Serving to give force or emphasis; as, an intensive verb or preposition.

(2):

(n.) That which intensifies or emphasizes; an intensive verb or word.

(3):

(a.) Stretched; admitting of intension, or increase of degree; that can be intensified.

(4):

(a.) Characterized by persistence; intent; unremitted; assiduous; intense.

(5):

(a.) Designating, or pertaining to, any system of farming or horticulture, usually practiced on small pieces of land, in which the soil is thoroughly worked and fertilized so as to get as much return as possible; - opposed to extensive.