The last three days of Holy Week are referred to as the Easter or Sacred Triduum (Triduum Sacrum), the three-part drama of Christ's redemption: Holy Thursday, Good Friday and Holy Saturday.
Holy Thursday is also known as "Maundy Thursday." The word maundy comes from the Latin word mandatum (commandment) which is the first word of the Gospel acclamation:
Mandátum novum do vobis dicit Dóminus, ut diligátis ínvicem, sicut diléxi vos. "I give you a new commandment: Love one another as I have loved you." (John 13:34)These are the words spoken by our Lord to His apostles at the Last Supper, after he completed the washing of the feet. We should imitate Christ's humility in the washing of the feet.
By meditating on the Gospels (cf. Matt 26:1 ff.; Mark 14:1 ff.; Luke 22:1 ff.; John 13:1 ff.), we can recall to mind Jesus' actions of that day. Father Bernard Strasser summarizes all the events of that first Holy Thursday:
...They included: (1) the eating of the Easter lamb or the paschal meal; (2) the washing of the disciple's feet; (3) the institution of the Most Holy Eucharist (the first Mass at which Jesus Christ, the eternal high priest, is the celebrant; the first Communion of the apostles; the first conferring of Holy Orders); (4) the foretelling of Judas' betrayal and Peter's denials; (5) the farewell discourse and priestly prayer of Jesus; (6) the agony and capture of Jesus in the Garden of Olives. — ©1947, With Christ Through the YearIn all the German speaking countries, Slavic nations and in Hungary this day is also known as "Green Thursday." The word is a corruption of the German word grunen (to mourn) to the German word for green (grün). Many people believe they must eat green at today's meal, which is probably derived from from the Jewish Passover meal that included bitter herbs.