Maundy Thursday is derived from the words of Jesus in the Gospel of John, referring to the "new commandment" he gave his apostles.
In the English speaking world, many call Holy Thursday “Maundy Thursday.”
What does that mean?
The word Maundy is related to the Latin word, “mandatum,” and is found in the liturgy during the washing of the feet.
Dom Prosper Gueranger explains this meaning in his Liturgical Year.
The Ceremony of the Washing of the Feet is also called the Mandatum, from the first word of the first Antiphon … Mandatum novum do vobis.
This antiphon is taken from the Gospel of John and repeats the words of Jesus to his Apostles.
A newcommandment I give to you, that you love one another; even as I have loved you, that you also love one another.John 13:34
“Maundy Thursday” is then translated as “Commandment Thursday,” a reference to the “new commandment” Jesus proclaimed, focused on loving others as Jesus loves us.