/ ˈʌmbrə; NAmE / noun ( pl. um·bras or um·brae / ˈʌmbriː; NAmE /) ( technical )
1.
the darkest part of a shadow
2.
the area on the earth or the moon which is the darkest during an eclipse
—compare penumbra
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WORD ORIGIN
late 16th cent. (denoting a phantom or ghost): from Latin , literally shade .