Available Definitions:
1) n. - Of or pertaining to the science of vision; optical.
2) n. - Pertaining to the art, or in accordance with the laws, of perspective.
3) a. - A glass through which objects are viewed.
4) a. - That which is seen through an opening; a view; a vista.
5) a. - The effect of distance upon the appearance of objects, by means of which the eye recognized them as being at a more or less measurable distance. Hence, aerial perspective, the assumed greater vagueness or uncertainty of outline in distant objects.
6) a. - The art and the science of so delineating objects that they shall seem to grow smaller as they recede from the eye; -- called also linear perspective.
7) a. - A drawing in linear perspective.