Definition of umbra noun from the Oxford Advanced Learner's Dictionary

     

    umbra

     noun
    noun
    BrE BrE//ˈʌmbrə//
     
    ; NAmE NAmE//ˈʌmbrə//
     
    (pl. umbras, umbrae
    BrE BrE//ˈʌmbriː//
     
    ; NAmE NAmE//ˈʌmbriː//
     
    )
    (specialist)
     
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  1. 1the darkest part of a shadow
  2. 2the area on the earth or the moon which is the darkest during an eclipse compare penumbra
  3. Word Origin late 16th cent. (denoting a phantom or ghost): from Latin, literally ‘shade’.
See the Oxford Advanced American Dictionary entry: umbra