The word, liturgy in the Christian tradition means the participation of the People of God "in the work of God" Through the litugy Christ, our redeemer and high priest, continues the work of redemption in, with, and through his Church. (CCC1069)
The liturgy is also a participation in Christ's own prayer addressed to the Father in the Holy Spirit.  In the liturgy, all Christian prayer finds its source and goal Through the liturgy the inner man is rooted and grounded in "the great love with which the Father loved us in His beloved Son. (CCC1073)