What is "purlie"

Purlie is a musical with a book by Ossie Davis, Philip Rose, and Peter Udell, lyrics by Udell, and music by Gary Geld. It is based on Davis's 1961 play Purlie Victorious, which was later made into the 1963 film Gone Are the Days! and which included all of the original Broadway cast, including Ruby Dee, Alan Alda, Beah Richards, and Godfrey Cambridge.