| 单词 | penumbra |
| 释义 | penumbra (once / 27360 pages) n When you measure your shadow to calculate the angle of the sun in the sky, be sure to measure to the edges of your shadow, to the penumbra, the part of a shadow that is not as dark as the center. You're likely to come across penumbra most often in astronomy, as with an eclipse, where shadow is a defining feature. In a lunar eclipse, the edge of the earth's shadow — the part that isn't fully dark — is its penumbra. Sun spots also have a penumbra, the outer edge that's not quite as dark as the center. The word comes from the Latin root umbra, which means "shadow." The pen part means "almost," so a penumbra is "almost shadow." WORD FAMILYpenumbra: penumbrae, penumbras USAGE EXAMPLESMuch of the Alt-Right’s output will seem indecipherably weird to those unfamiliar with the darker penumbras of popular culture. Economist(Sep 15, 2016) But such moments were tempered by the long penumbra cast by Everest, which seemed to recede little with the passage of time. Jon Krakauer, Into Thin Air(1996) Democrats have no intention of letting Republicans escape from the penumbra of Mr. Trump. New York Times(Jul 17, 2016) n a fringe region of partial shadow around an umbra Hyper shadow shade within clear boundaries |
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