1. (logic) denoting the relation between particular affirmative and particular negative propositions, where both may be true but only one can be false
   "The statements 'Some cats are black' and 'Some cats are not black' are subcontrary"

1. (logic) a proposition that may be true together with another proposition but cannot both be false
   "In traditional logic, 'Some S is P' and 'Some S is not P' are subcontraries"

Derived forms: subcontraries

Encyclopedia: Subcontrary