The word conjugation has several meanings:

• Grammatical conjugation is the modification of a verb from its basic form.
  • In the Latin language, different verbs have complex conjugation rules. See Latin conjugation.
• In biology, conjugation is sexual reproduction involving interchange of DNA between cells, rather than their fusion. Various forms of conjugation exist in different groups, such as bacteria (see bacterial conjugation) and ciliates.
• In mathematics, the term is used in two senses:
  • complex conjugation is the operation which multiplies the imaginary part of a complex number by -1.
  • if a is an element of a group, then the map f(x) = axa^-1 is called conjugation by a. See inner automorphism, conjugacy class and conjugate closure
• In organic chemistry, conjugation is the interaction between two carbon-carbon double bonds, increasing stability and thereby lowering the overall energy of the molecule. The system formed is called a conjugated system.

See also: conjugate