1. The oath of allegiance taken by roman soldiers; hence, a sacred ceremony used to impress an obligation; a solemn oath-taking; an oath. I’ll take the sacrament on’t. (Shak)
2. The pledge or token of an oath or solemn cobenant; a sacred thing; a mystery. God sometimes sent a light of fire, and pillar of a cloud . . . And the sacrament of a rainbow, to guide his people through their portion of sorrows. (Jer. Taylor)
3. One of the solemn religious ordinances enjoined by christ, the head of the Christian church, to be observed by his followers; hence, specifically, the eucharist; the Lord’s Supper.
Synonym: Sacrament, eucharist.
protestants apply the term sacrament to baptism and the Lord’s Supper, especially the latter. The R. Cath. And greek churches have five other sacraments, viz, confirmation, penance, holy orders, matrimony, and extreme unction. As sacrament denotes an oath or vow, the word has been applied by way of emphasis to the Lord’s Supper, where the most sacred vows are renewed by the Christian in commemorating the death of his Redeemer. Eucharist denotes the giving of thanks; and this term also has been applied to the same ordinance, as expressing the grateful remembrance of Christ’s sufferings and death. Some receive the sacrament as a means to procure great graces and blessings; others as an eucharist and an office of thanksgiving for what they have received.
Origin: L. Sacramentum an oath, a sacred thing, a mystery, a sacrament, fr. Sacrare to declare as sacred, sacer sacred: cf. F. Sacrament. See Sacred.
Source: Websters Dictionar