1590s, "phantom, ghost," a figurative use from Latin umbra "shade, shadow" (see umbrage). Astronomical sense of "shadow cast by the earth or moon during an eclipse" is first recorded 1670s. Meaning "an uninvited guest accompanying an invited one" is from 1690s in English, from a secondary sense among the Romans. Related: Umbral.
实用例句
1. This includes the continuous survey of umbra and penumbra of the sunspot.
这包括对太阳黑子本影和半影持续的观测.来自辞典例句
2. This is a lighter area between the umbra and the edge of a shadow.
这是本影和阴影边缘之间较亮的区域.来自辞典例句
3. Only moon umbra totally puts on earth, the shadow area can watch the eclipse.
唯有在月球的本影投影在地球表面时, 在该区域的人才能够观测到日食.来自互联网
4. Umbra - You need Samples values equal to or greater than 2 to see any influence of this button.
