Describes a relationship or property where two things are mutual or inversely related. Often used in technical or formal contexts.
この契約には相反性の原則が適用される。
The principle of reciprocity applies to this contract.
両者の関係は相反性に基づいている。
Their relationship is based on mutuality.
Compound of 相反 (sōhan, 'reciprocal, opposite') and 性 (sei, 'nature, property'). The exact historical derivation is uncertain, but the term is used in modern technical vocabulary.