Altar. From the Latin word altar (= altar) but of uncertain etymology.
As the General Instruction of the Roman Missal (no. 296) states “The altar on which the Sacrifice of the Cross is made present under sacramental signs is also the table of the Lord to which the People of God is called together to participate in the Mass, as well as the center of the thanksgiving that is accomplished through the Eucharist”. The Altar is the center of liturgical space and “of the whole Liturgy of the Eucharist” (cf. GIRM no. 73), where the Savior’s sacrifice is consumed and perpetuated. And “it is appropriate to have a fixed altar in every church, since it more clearly and permanently signifies Christ Jesus, the living stone (1Pt2:4; cf. Eph 2:20).” (cf. GIRM no. 298).
The oldest fixed altars are always quadrangular tables.
“The practice of placing relics of Saints, even those not Martyrs, under the altar to be dedicated is fittingly retained”( GIRM no. 302).