The Collaborative International Dictionary of English v.0.48:
Approximative \Ap*prox"i*ma*tive\, a. [Cf. F. approximatif.] Approaching; approximate. -- Ap*prox"i*ma*tive*ly, adv. -- Ap*prox"i*ma*tive*ness, n. [1913 Webster]WordNet (r) 3.0 (2006):
approximative adj 1: not quite exact or correct; "the approximate time was 10 o'clock"; "a rough guess"; "a ballpark estimate" [syn: approximate, approximative, rough]