Lord’s Supper
One of the two sacraments (or ordinances) that Jesus commanded his church to observe; a ceremonial meal instituted by Christ to commemorate his death on the cross and celebrate “the new covenant relationship with God through Christ’s death”;1also called Communion, the Eucharist.

• From scripture: 
  

  And he took a cup, and when he had given thanks he said, “Take this, and divide it among yourselves.  For I tell you that from now on I will not drink of the fruit of the vine until the kingdom of God comes.” And he took bread, and when he had given thanks, he broke it and gave it to them, saying, “This is my body, which is given for you. Do this in remembrance of me.” And likewise the cup after they had eaten, saying, “This cup that is poured out for you is the new covenant in my blood. (Luke 22:17-20 ESV)

• From Keach’s Catechism:

  Q. 107. What is the Lord’s Supper?

  A. The Lord’s Supper is a holy ordinance, wherein, by giving and receiving bread and wine, according to Christ’s appointment, His death is showed forth, and the worthy receivers are, not after a corporeal and carnal manner, but by faith, made partakers of His body and blood, with all His benefits, to their spiritual nourishment, and growth in grace.

  Q. 108. What is required to the worthy receiving of the Lord’s Supper?

  A. It is required of them that would worthily (that is, suitably) partake of the Lord’s Supper, that they examine themselves, of their knowledge to discern the Lord’s body; of their faith to feed upon Him; of their repentance, love, and new obedience: lest, coming unworthily, they eat and drink judgment to themselves.

• From Systematic Theology by Louis Berkhof, a list of the things signified in the Lord’s Supper:

 a. It is a symbolical representation of the Lord’s death, 1 Cor. 11:26. The central fact of redemption, prefigured in the sacrifices of the Old Testament, is clearly set forth by means of the significant symbols of the New Testament sacrament. The words of the institution, “broken for you” and “shed for many”, point to the fact that the death of Christ is a sacrificial one for the benefit, and even in the place, of His people.

b. It also symbolizes the believer’s participation in the crucified Christ. In the celebration of the Lord’s Supper the participants not merely look at the summons, but receive them and feed upon them. Figuratively speaking, they “eat the flesh of the Son of Man, and drink His blood,” John 6:53, that is, they symbolically appropriate the benefits secured by the sacrificial death of Christ.

c. It represents, not only the death of Christ as the object of faith, and the act of faith which unites the believer to Christ, but also the effect of this act as giving life, strength, and joy, to the soul. This is implied in the emblems used. Just as bread and wine nourish and invigorate the bodily life of man, so Christ sustains and quickens the life of the soul. Believers are regularly represented in Scripture as having their life, and strength, and happiness, in Christ.

d. Finally, the sacrament also symbolizes the union of believers with one another. As members of the mystical body of Jesus Christ, constituting a spiritual unity, they eat of the same bread and drink of the same wine, I Cor. 10:17; 12:13. Receiving the elements, the one from the other, they exercise intimate communion with one another.