Conjugation or conjugate may refer to:
- Grammatical conjugation, the modification of a verb from its basic form
- Conjugate (algebra), used to rationalize the denominator of a fraction
- Conjugated systems of p-orbitals in chemical molecules
- Conjugation (biochemistry), the turning of substances into a hydrophilic state in the body
- Conjugation (acid-base theory), a system describing a conjugate acid-base pair
- Conjugation (group theory), the image of an element under the conjugation homomorphisms
- Conjugate (graph theory), an alternative term for a line graph