What's the "een" in Halloween?
late 14c., "science of optics," from Old French perspective and directly from Medieval Latin perspectiva ars "science of optics," from fem. of perspectivus "of sight, optical" from Latin perspectus "clearly perceived," past participle of perspicere "inspect, look through, look closely at," from per- "through" (see per) + specere "look at" (see scope (n.1)). Sense of "art of drawing objects so as to give appearance of distance or depth" is first found 1590s, influenced by Italian prospettiva, an artists' term. The figurative meaning "mental outlook over time" is first recorded 1762.
In drawing or painting, a way of portraying three dimensions on a flat, two-dimensional surface by suggesting depth or distance.