The Collaborative International Dictionary of English v.0.48:

Hexastich \Hex"a*stich\, Hexastichon \Hex*as"ti*chon\, n. [L.
   hexastichus of six rows, lines, or verses, Gr. ?; "e`x six +
   sti`chos row, line, verse.]
   A poem consisting of six verses or lines.
   [1913 Webster]