obscuration noun2 •The state of being obscured.At eleven the room darkened, the moon having climbed behind a tree. But the tree being small, and the moon's ascension rapid, this transit was brief, and this obscuration. — 1953 •A unit of measurement used in particular for smoke detectors which respond to absorption of light by smoke, in percent absorption per unit length, e.g. % obs/ft, % obs/m. formsobscurations
