contraries Meaning, Definition & Usage

  1. noun a relation of direct opposition
    contrary; reverse; opposite.
    • we thought Sue was older than Bill but just the reverse was true
  2. noun exact opposition
    contrary.
    • public opinion to the contrary he is not guilty
  3. noun a logical relation such that two propositions are contraries if both cannot be true but both can be false
    contrary.

WordNet

Con"tra*ries noun plural
Etymology
Pl. of Contrary, n.
Definitions
  1. (Logic) Propositions which directly and destructively contradict each other, but of which the falsehood of one does not establish the truth of the other.
    If two universals differ in quality, they are contraries; as, every vine is a tree; no vine is a tree. These can never be both true together; but they may be both false. I. Watts.

Webster 1913