In the Orthodox liturgical tradition, the antimension (Greek "instead of the table") is one of the furnishings of the altar. It is a rectangular piece of cloth, of linen or silk, with representations of the entombment of Christ, the four evangelists, and scriptural passages related to the Eucharist. It often has a very small relic sewn into it. It is unfolded on the altar before the anaphora, and the Eucharist is consecrated on it. The antimension must be consecrated and signed by the bishop, indicating his permission for the Eucharist to be celebrated in his absence. It is, in effect, the priest's permission to officiate.

The antimension is a substitute altar. A priest may celebrate the Eucharist on the antimension even if there is no porperly consecrated altar. In emergencies, war and persecution, the antimension serves a very important pastoral need. Current liturgical use, is that the priest always uses the antimension. However, in the past, if the priest celebrated at a consecrated altar, the sacred elements were placed on another cloth, the eileton, answering to the western corporal. The eileton is now often used to wrap the antimension when it is not in use.

A wooden tablet, the ţablîtho, is the liturgical equivalent of the antimension in the churches of Syriac tradition. However, it is no longer used by the Antiochian Orthodox Church (which uses the antimension) or the Assyrian Church of the East and Chaldean Catholic Church.

In the Ethiopian Tawahedo Church, the tâbot is functionally similar to the tablitho. However, this word is also used in the Ge'ez language to describe the Ark of the Covenant. The Ark is symbolically represented by the manbara tâbôt ('throne of the Ark'), a casket that sits on the altar. The tabot itself, the wooden tablet, is taken out before the anaphora, and symbolizes the giving of the Ten Commandments.