Maundy — as in Maundy Thursday — comes from the Latin mandatum. This is the first word of the phrase “Mandatum novum do vobis ut diligatis invicem sicut dilexi vos.” It means A new commandment I give unto you, That ye love one another; as I have loved you which is how Jesus in John 13:34 explained to the Apostles the significance of his washing their feet the night before His crucifixion.