§1360
Sacraments › … › V. The Sacramental Sacrifice Thanksgiving, Memorial, Presence
Thanksgiving and praise to the Father
The Eucharist is a sacrifice of thanksgiving to the Father, a blessing by which the Church expresses her gratitude to God for all his benefits, for all that he has accomplished through creation, redemption, and sanctification. Eucharist means first of all "thanksgiving."
Source: Catechism of the Catholic Church (Vatican.va)