adj. & n.
adj. 1 thorough, vigorous; directed to a single point, area, or subject (intensive study; intensive bombardment). 2 of or relating to intensity as opp. to extent; producing intensity. 3 serving to increase production in relation to costs (intensive farming methods). 4 (usu. in comb.) Econ. making much use of (a labour-intensive industry). 5 Gram. (of an adjective, adverb, etc.) expressing intensity; giving force, as really in my feet are really cold.
n. Gram. an intensive adjective, adverb, etc. intensive care medical treatment with constant monitoring etc. of a dangerously ill patient (also (with hyphen) attrib.: intensive-care unit). intensively adv. intensiveness n.
[ F intensif -ive or med.L intensivus (as INTEND) ]