Source : Webster's Revised Unabridged Dictionary (1913)

Properispomenon \Pro*per`i*spom"e*non\, n.; pl.
   {Properispomena}. [NL., fr. Gr. ?, fr. ? to circumflex on the
   penult; ? before + ? to circumflex. See {Perispomenon}.] (Gr.
   Gram.)
   A word which has the circumflex accent on the penult.