Source : Webster's Revised Unabridged Dictionary (1913)

Isochronal \I*soch"ro*nal\, a. [See {Isochronous}.]
   Uniform in time; of equal time; performed in equal times;
   recurring at regular intervals; isochronal vibrations or
   oscillations.

Source : WordNet®

isochronal
     adj : equal in duration or interval; "the oscillations were
           isochronal" [syn: {isochronous}]