I saw a church sign last week in Bellingham with a list of Holy Week services, including one for "Maunday" Thursday. I remember the first time I heard anyone say "Maundy Thursday"; I thought they were saying "Monday Thursday," which made no sense at all. But the word "Maundy" is never heard in any other context, so it's no wonder it's unfamiliar. Wikipedia says "Maundy" either derives from the Latin mandatum, as in Mandatum novum do vobis ut diligatis invicem sicut dilexi vos, meaning "A new commandment I give unto you, that ye love one another as I have loved you," which Jesus said to his disciples at their seder supper, or else it's from the Latin mendicare or French mendier: to beg.
Which brings me to my point. Actually, I don't have a point.* I just find etymologies interesting.