The Collaborative International Dictionary
Clinopinacoid
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.
Wiktionary
clinopinacoid
n. (context crystallography English) The plane in monoclinic crystals that is parallel to the vertical and the inclined lateral (clinidiagonal) axis.