The Collaborative International Dictionary of English v.0.48:
Omissive \O*mis"sive\, a. [See Omit.] Leaving out; omitting. --Bp. Hall. -- O*mis"sive*ly, adv. [1913 Webster]WordNet (r) 3.0 (2006):
omissive adj 1: characterized by omissions; "omissive crimes"