Term used in the theory of the syllogism for a transformation in which the original predicate is made the subject of a proposition, and vice versa. Conversion is sometimes straightforward (with an E or an I proposition): ‘some As are B’ is equivalent to ‘some Bs are A’. But ‘all As are B’ can only be converted with a shift in the figure, being deemed equivalent to ‘some Bs are A’.
Philosophy dictionary. Academic. 2011.