- Mathematics joined in a reciprocal relation, especially having the same real parts and equal magnitudes but opposite signs of imaginary parts. Short for complex conjugate.
- a mathematical value or entity having a reciprocal relation with another. See also complex conjugate.
late 15th century (as an adjective): from Latin conjugat- 'yoked together', from the verb conjugare, from con- 'together' + jugum 'yoke'