(chiefly historical, also figurative) A pardon of a sin; the forgiveness of an offence, or relinquishment of a (legal) claim or a debt.

A reduction or cancellation of a penalty for a criminal offense or a lessening of the manifestations of a disease.

A noun "remission" refers to the act of remitting, returning, or sending back, particularly in the context of law where it can also mean the referral of a case back to another court.

(spectroscopy) Reflection or scattering of light by a material; reemission.

(transitive) To change the mission of; to provide with a new mission.