What Christmas carol is to the tune of Greensleeves?

The Christmas carol that is set to the tune of "Greensleeves" is "What Child Is This?" The lyrics were written by William Chatterton Dix in the 19th century, and the melody is derived from the traditional English folk song "Greensleeves." The carol reflects on the birth of Jesus and invites contemplation of his significance. It's a popular piece during the Christmas season.