n. pl. um·bras or um·brae (-brē)
1. A dark area, especially the blackest part of a shadow from which all light is cut off.
a. The completely dark central portion of the shadow cast by the earth, moon, or other body during an eclipse.
b. The darkest region of a sunspot.
(click for a larger image)umbra
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.