from
The Collaborative International Dictionary of English v.0.48
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.
[1913 Webster]
{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.
[1913 Webster]