Eucharist, meaning “thankful, grateful” here refers to Holy Communion or the Body and Blood of Christ, which is consumed during the Catholic Mass or Eucharistic Celebration. "At the Last Supper, on the night he was betrayed, our Savior instituted the Eucharistic sacrifice of his Body and Blood, ... a memorial of his death and resurrection: a sacrament of love, a sign of unity, a bond of charity, a Paschal banquet 'in which Christ is consumed, the mind is filled with grace, and a pledge of future glory is given to us.'" As such, Eucharist is "an action of thanksgiving to God" derived from "the Jewish blessings that proclaim – especially during a meal – God's works: creation, redemption, and sanctification."

Blessed Sacrament is a devotional term used in the Roman Catholic Church to refer to the Eucharistic species (the Body and Blood of Christ). Consecrated hosts are kept in a tabernacle after Mass, so that the Blessed Sacrament can be brought to the sick and dying outside the time of Mass. This makes possible also the practice of eucharistic adoration. Because Christ himself is present in the sacrament of the altar, he is to be honored with the worship of adoration. "To visit the Blessed Sacrament is ... a proof of gratitude, an expression of love,... and a display of adoration toward Christ our Lord."