Apse
An altar is actually called "the altar", although if there are many altars in a Church, they may be called by a specific name, like the main altar, the high altar, the side altar, the Blessed Virgin Mary altar, the altar of repose, the Blessed Sacrament altar, the St. Joseph altar, etc.
An altar cloth.The altar cloth
The altar in the courtyard of the Tabernacle was called the Brazen Altar or the Altar of Burnt Offering. It was made of bronze and used for offering sacrifices, including burnt offerings, to God. This altar was central to the sacrificial system in ancient Israel, symbolizing atonement and worship.
Its called an apse.
The hanging cloth on an altar is called an altar cloth or an altar frontal. It is used to decorate the altar and often changes according to the liturgical season or special occasions in the church.
An altar.
Apse
The opposite of an altar might be a sacrificial table. Also, the altar is in the eastern portion of the church. The portion in the western part opposite to the altar in a church is called the entryway or vestibule.
it is called the ambulatory.
When a bride or groom is left at the altar it is generally called 'left at the altar,' but, the other word would be 'jilted.'
There isn't really an "altar" in a mosque in the way that churches have one. There is a small recession in one wall, called a "mihrab" that indicates the direction to pray, and there is a platfrom that the imam sits on when giving a sermon, which is called a "mimbar," but no altar.
The young priest assigned to a parish to help the pastor is called a curate. The young men who assist the priest at the altar are called altar boys, or sometimes altar servers if the priest in question insists on letting girls help.