monoclinic

adjective Crystallography.

1. noting or pertaining to a system of crystallization in which the crystals have three unequal axes, with one oblique intersection.

adjective

1. crystallog relating to or belonging to the crystal system characterized by three unequal axes, one pair of which are not at right angles to each other

1. Relating to a crystal having three axes of different lengths. Two of the axes are at oblique angles to each other, and the third axis is perpendicular to the plane that is made by the other two. The mineral gypsum has monoclinic crystals. See illustration at crystal.