Magisterium (from the Latin magister: 'master') is a technical ecclesiastical term in Catholicism referring to the authority of the Catholic Church to teach the truths of the faith infallibly.

Informally, magisterium refers to the consensus of the faith as it has been historically taught and believed over two millennia. This informal magisterium is from time to time formally or solemnly ratified by the dogmatic definitions issued ex cathedra by the pope, or by the bishops in council, provided that their decisions are accepted and approved by the pope.