A region on the ventral side of the brain, either just back of the pons Varolii, or, as in man, covered by the posterior extension of its transverse fibers
A four-sided polygon with no parallel sides and no sides equal; a simple convex irregular quadrilateral
the wrist bone on the thumb side of the hand that articulates with the 1st and 2nd metacarpals a multiple star in the constellation of Orion a quadrilateral with no parallel sides