Source : Webster's Revised Unabridged Dictionary (1913)

Clinopinacoid \Cli`no*pin"a*coid\, n. [Gr. kli`nein to incline +
   E. pinacoid.] (Crystallog.)
   The plane in crystals of the monoclinic system which is
   parallel to the vertical and the inclined lateral
   (clinidiagonal) axes.