The Collaborative International Dictionary of English v.0.48:

Stylite \Sty"lite\ (st[imac]"l[imac]t), n. [Gr. styli`ths, fr.
   sty^los a pillar.] (Eccl. Hist.)
   One of a sect of anchorites in the early church, who lived on
   the tops of pillars for the exercise of their patience; --
   called also pillarist and pillar saint.
   [1913 Webster]

         The two other holy men in Gregory's narrative had more
         exotic origins than the pair that has just been seen.
         Gregory encountered one of them when on a journey to
         the north-eastern parts of the Frankish kingdom. This
         was a Lombard, named Vulfolaic, who had spent some
         years in the arduous exercise of being a stylite, the
         Christian equivalent of a flagpole sitter; in other
         words, Vulfolaic was a monk whose main austerity
         consisted in living on top of a pillar. By carrying out
         this feat in the rain, snow, and frost of the Moselle
         valley, Vulfolaic had convinced the local population to
         overthrow and abandon the idol of Diana to which they
         were addicted.                           --Walter
                                                  Goffart,
                                                  FOREIGNERS IN
                                                  THE HISTORIES
                                                  OF GREGORY OF
                                                  TOURS
                                                  (http://www.arts.uwo.ca/florilegium/goffart.html).

WordNet (r) 3.0 (2006):

stylite
    n 1: an early Christian ascetic who lived on top of high pillars