Source : Webster's Revised Unabridged Dictionary (1913)

Pentacle \Pen"ta*cle\, n. [Gr. ? five.]
   A figure composed of two equilateral triangles intersecting
   so as to form a six-pointed star, -- used in early ornamental
   art, and also with superstitious import by the astrologers
   and mystics of the Middle Ages.

Source : WordNet®

pentacle
     n : a star with 5 points; formed by 5 straight lines between the
         vertices of a pentagon and enclosing another pentagon
         [syn: {pentagram}]