Webster's English Dictionary

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umbra

um.bra \'*m-br*\ \-(.)bre-, -.bri-\ n or umbras or um.brae [L] pl  1: a 
   shaded area  2a: a conical shadow excluding all light from a given source; 
   specif  : the conical part of the shadow of a celestial body excluding all 
   light from the primary source 2b1: PENUMBRA  2b2: the central dark part of 
   a sunspot