Source : Webster's Revised Unabridged Dictionary (1913)

Lunitidal \Lu"ni*tid`al\, a.
   Pertaining to tidal movements dependent on the moon. --Bache.

   {Lunitidal interval}. See {Retard}, n.

Source : WordNet®

lunitidal interval
     n : interval between the moon's transit of a particular meridian
         and the next high tide at that meridian