Obversion n. : The act of turning toward or downward.

Obversion n. : The act of immediate inference, by which we deny the opposite of anything which has been affirmed; as, all men are mortal; then, by obversion, no men are immortal. This is also described as "immediate inference by privative conception."

Example:
what's the Obversion,conversion,contraposition of this sentence?

Taxonomy
obversion, affirmative, animals, predicate, Macmillan, cats, non-P, Introduction to Logic, creatures, Copi, free encyclopedia, categorical propositions, quantity, Irving, inference, versa, obverse, complements.

Defination from the web:
obversion is a "type of immediate inference in which from a given proposition another proposition is inferred whose subject ... In the obversion of a particular negative to a particular affirmative the quantity of the subject also remains unchanged, and the predicate term ...