Source : Webster's Revised Unabridged Dictionary (1913)

   {Retard, or Age}, {of the tide}, the interval between the
      transit of the moon at which a tide originates and the
      appearance of the tide itself. It is found, in general,
      that any particular tide is not principally due to the
      moon's transit immediately proceeding, but to a transit
      which has occured some time before, and which is said to
      correspond to it. The retard of the tide is thus
      distinguished from the lunitidal interval. See under
      {Retardation}. --Ham. Nav. Encyc.