caus·a·tive (kô?z?-t?v)adj.1. Functioning as an agent or cause.2. Expressing causation. Used of a verb or verbal affix.caus?a·tive n.caus?a·tive·ly adv.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.