The Collaborative International Dictionary of English v.0.48:

Tallith \Tal"lith\, n. [NHeb. tall[imac]th.] (Jewish Costume)
   (a) An undergarment worn by orthodox Jews, covering the chest
       and the upper part of the back. It has an opening for the
       head, and has tassels, called zizith, on its four
       corners.
   (b) A tasseled shawl or scarf worn over the head or thrown
       round the shoulders while at prayer.
       [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

tallith
    n 1: (Judaism) a shawl with a ritually knotted fringe at each
         corner; worn by Jews at morning prayer [syn: prayer
         shawl, tallith, tallis]