The Collaborative International Dictionary
Illative sense
Illative \Il"la*tive\, a. [L. illativus: cf. F. illatif.] Relating to, dependent on, or denoting, illation; inferential; conclusive; as, an illative consequence or proposition; an illative word, as then, therefore, etc.
Illative conversion (Logic), a converse or reverse statement of a proposition which in that form must be true because the original proposition is true.
Illative sense (Metaph.), the faculty of the mind by which it apprehends the conditions and determines upon the correctness of inferences.