that part of grammar which teaches the nature and affections of letters, and the just method of spelling or writing words, with all the proper and necessary letters, making one of the four greatest divisions or branches of grammar. See GRAMMAR.

ORTHOGRAPHY, in Geometry, the art of drawing or delineating the fore-right plan of any object, and of expressing the heights or elevations of each part. It is called Orthography, for its determining things by perpendicular lines falling on the geometrical plane.

ORTHOGRAPHY, in Architecture, the elevation of a building.

ORTHOGRAPHY, in Perspective, is the fore-right side of any plane, i.e. the side or plane that lies parallel to a straight line, that may be imagined to pass through the outward convex points of the eyes, continued to a convenient length.

ORTHOPOEIA, a species or degree of asthma, where there is such a difficulty of respiration that the patient is obliged to sit or stand upright in order to be able to breathe. See MEDICINE Index.