- (n.) The part of a picture where the shade imperceptibly blends with the light.
- (n.) The shadow cast, in an eclipse, where the light is partly, but not wholly, cut off by the intervening body; the space of partial illumination between the umbra or perfect shadow, on all sides, and the full light.
- (n.) An incomplete or partial shadow.
Webster's Revised Unabridged Dictionary
| APA | Webster's. (2011). penumbra. Retrieved September 26, 2026, from http://smartdefine.org/penumbra/definitions/2043525 |
| Chicago | Webster's. 2011. "penumbra" http://smartdefine.org/penumbra/definitions/2043525 (accessed September 26, 2026). |
| Harvard | Webster's 2011, penumbra, Smart Define, viewed 26 September, 2026, <http://smartdefine.org/penumbra/definitions/2043525>. |
| MLA | Webster's. "penumbra" 27 May 2011. Web. 26 September 2026. <http://smartdefine.org/penumbra/definitions/2043525> |