Meaning of isoionic point

i'so•i•on'ic point'

Pronunciation: (ī'sō-ī-on'ik, ī"sō-), [key]
— Chem. Chem.
  1. the hydrogen ion concentration at which the concentration of the dipolar ion is at a maximum.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.