The Collaborative International Dictionary of English v.0.48:

Persis \Per"sis\, n. [Etymol. uncertain.]
   A kind of coloring matter obtained from lichens.
   [1913 Webster]

Easton's 1897 Bible Dictionary:

Persis
   a female Christian at Rome whom Paul salutes (Rom. 16:12). She
   is spoken of as "beloved," and as having "laboured much in the
   Lord."


Hitchcock's Bible Names Dictionary (late 1800's):

Persis, same as Persia