subcontrary

UK: /sʌbˈkɒntrərɪ/ US: (sub kon′trer ē)

WordReference Random House Unabridged Dictionary of American English © 2026

sub•con•tra•ry  (sub kon′trer ē), n., pl. -ries. [Logic.]

1. Philosophy one of two propositions that can both be true but cannot both be false.

• Medieval Latin subcontrārius, Late Latin (see sub-, contrary), origin, originally as translation of Greek hypenantíos
• 1595–1605

Collins Concise English Dictionary © HarperCollins Publishers::

subcontrary / sʌbˈkɒntrərɪ/ adjective

1. (of a pair of propositions) related such that they cannot both be false at once, although they may be true together
   Compare contrary5, contradictory3

noun ( -ries)

1. a statement that cannot be false when a given statement is false