The Collaborative International Dictionary of English v.0.48:

Umbra \Um"bra\, n.; pl. Umbrae. [L., a shadow.]
   1. (Astron.)
      (a) The conical shadow projected from a planet or
          satellite, on the side opposite to the sun, within
          which a spectator could see no portion of the sun's
          disk; -- used in contradistinction from penumbra. See
          Penumbra.
      (b) The central dark portion, or nucleus, of a sun spot.
      (c) The fainter part of a sun spot; -- now more commonly
          called penumbra.
          [1913 Webster]

   2. (Zool.) Any one of several species of sciaenoid food
      fishes of the genus Umbrina, especially the
      Mediterranean species (Umbrina cirrhosa), which is
      highly esteemed as a market fish; -- called also ombre,
      and umbrine.
      [1913 Webster]

   Umbra tree (Bot.), a tree (Phytolacca dioica) of the same
      genus as pokeweed. It is native of South America, but is
      now grown in southern Europe. It has large dark leaves,
      and a somber aspect. The juice of its berries is used for
      coloring wine. --J. Smith (Dict. Econ. Plants).
      [1913 Webster]

WordNet (r) 3.0 (2006):

Phytolacca dioica
    n 1: fast-growing herbaceous evergreen tree of South America
         having a broad trunk with high water content and dark green
         oval leaves [syn: ombu, bella sombra, Phytolacca
         dioica]