Transubstantiation

Transubstantiation is the Catholic doctrine that, in the Eucharist, the substance of bread and wine becomes Christ’s body and blood while their sensible appearances remain.

Substance and accidents: A distinction in Aristotelian philosophy between what a thing is and its perceptible properties. Catholic explanations use this distinction to say Christ’s body and blood are present while bread and wine still appear.
Paschasius Radbertus: A ninth-century Benedictine theologian who wrote an influential treatise on Christ’s body and blood in the Eucharist. His work helped intensify medieval discussion of Eucharistic change.
Consubstantiation: A term commonly used for the view that Christ’s body and blood coexist with bread and wine in the Eucharist. It contrasts with the Catholic claim that the substances of bread and wine cease to remain.
Eucharistic adoration: A Catholic devotional practice of prayer before the consecrated Eucharistic host. Adoration follows from the belief that Christ is present in the consecrated elements.
Real presence: The Christian belief that Christ is truly present in the Eucharist. Transubstantiation specifies how Catholic teaching understands this presence.
Berengar of Tours: An eleventh-century theologian whose account of the Eucharist was condemned by church authorities. The controversy around his teaching prompted formal statements about Christ’s Eucharistic presence.
Sacramental union: The Lutheran teaching that Christ’s body and blood are truly present in the Eucharist with bread and wine. It affirms real presence without adopting the Catholic account of transubstantiation.
Benediction of the Blessed Sacrament: A Catholic rite in which a priest blesses the congregation with the consecrated host. The rite makes the doctrine’s implications for worship visible.
Eucharistic consecration: The liturgical prayer by which bread and wine are consecrated in the Eucharist. Catholic doctrine locates the change at the consecration.
Fourth Lateran Council: A 1215 ecumenical council that issued major definitions on church doctrine and governance. Its decree used the term transubstantiation to describe the Eucharistic change.

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