At the Last Supper, on the night he was betrayed, our Savior instituted the Eucharistic sacrifice of his Body and Blood. This he did in order to perpetuate the sacrifice of the cross throughout the ages until he should come again, and so to entrust to his beloved Spouse, the Church, 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.'”
The Eucharist is “the source and summit of the Christian life… It is the culmination both of God’s action sanctifying the world in Christ and of the worship men offer to Christ and through him to the Father in the Holy Spirit.”
Eucharist is so named because it is an action of thanksgiving to God.
The Greek words eucharistein and eulogein recall the Jewish blessings that proclaim – especially during a meal – God’s works: creation, redemption, and sanctification.
Above content is from The Catechism of the Catholic Church.