Where does the "Maundy" come from
Most scholars agree that the English word Maundy in that name for the day is derived through Middle English and Old French mandé, from the Latin mandatum, the first word of the phrase "Mandatum novum do vobis ut diligatis invicem sicut dilexi vos" ("A new commandment I give unto you, That ye love one another; as I have loved you"), the statement by Jesus in the Gospel of John 13:34 by which Jesus explained to the Apostles the significance of his action of washing their feet. The phrase is used as the antiphon sung in the Roman Rite during the "Mandatum" ceremony of the washing of the feet, which may be held during Mass or at another time as a separate event, during which a priest or bishop (representing Christ) ceremonially washes the feet of others, typically 12 persons chosen as a cross-section of the community. In 2016 it was announced that the Roman Missal had been revised to permit women to have their feet washed on Maundy Thursday; previously it permitted only males to do so.
Others theorize that the English name "Maundy Thursday" arose from "maundsor baskets" or "maundy purses" of alms which the king of England distributed to certain poor at Whitehall before attending Mass on that day. Thus, "maund" is connected to the Latin mendicare, and French mendier, to beg. A source from the Lutheran Church–Missouri Synod likewise states that, if the name was derived from the Latinmandatum, we would call the day Mandy Thursday, or Mandate Thursday, or even Mandatum Thursday; and that the term "Maundy" comes in fact from the Latin mendicare, Old French mendier, and English maund, which as a verb means to beg and as a noun refers to a small basket held out by maunders as they maunded.
Do Christians hold seder meals? As question that may have arisen during this time. A resource from ELCA website.
Further reading on the Seder Meal