Lewis & Short

1. pē̆tro, ōnis, m. [1. petra].

  1. I. A rustic: petrones rustici fere dicuntur, etc., Fest. p. 206, 23 Müll.; cf.: petrones rustici a petrarum asperitate et duritiā dicti, Paul. ex Fest. p. 207, 6 ib.
  2. II. An old wether, whose flesh is as hard as a stone (anteclass.), Plaut. Capt. 4, 2, 40.