Catechism of the Catholic Church
e. Para. 751: The word "Church" (Latin ecclesia, from the Greek ek-ka-lein, to "call out of") means a convocation or an assembly. It designates the assemblies of the people, usually for a religious purpose (Cf. Acts 19:39). . . . The equivalent Greek term Kyriake, from which the English word Church and the German Kirche are derived, means "what belongs to the Lord."
Para. 752: In Christian usage, the word "church" designates the liturgical assembly (Cf. 1 Cor. 11:18; 14:19, 28, 34, 35), but also the local community (Cf. 1 Cor 1:2; 16:1) or the whole universal community of believers (Cf. 1 Cor 15:9; Gal 1:13; Phil 3:6). These three meanings are inseparable. "The Church" is the People that God gathers in the whole world. She exists in local communities and is made real as a liturgical, above all a Eucharistic, assembly. She draws her life from the word and the Body of Christ and so herself becomes Christ's Body.