The Collaborative International Dictionary of English v.0.48:

Coma \Co"ma\, n. [L., hair, fr. Gr. ko`mh.]
   1. (Astron.) The envelope of a comet; a nebulous covering,
      which surrounds the nucleus or body of a comet.
      [1913 Webster]

   2. (Bot.) A tuft or bunch, -- as the assemblage of branches
      forming the head of a tree; or a cluster of bracts when
      empty and terminating the inflorescence of a plant; or a
      tuft of long hairs on certain seeds.
      [1913 Webster]

   Coma Berenices[L.] (Astron.), a small constellation north
      of Virgo; -- called also Berenice's Hair.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Berenice's Hair \Ber`e*ni"ce's Hair`\ [See Berenice's Locks,
   in Dictionary of Noted Names in Fiction.] (Astron.)
   See Coma Berenices, under Coma.
   [Webster 1913 Suppl.]

The Devil's Dictionary (1881-1906):

BERENICE'S HAIR, n.  A constellation (_Coma Berenices_) named in honor
of one who sacrificed her hair to save her husband.

    Her locks an ancient lady gave
    Her loving husband's life to save;
    And men -- they honored so the dame --
    Upon some stars bestowed her name.

    But to our modern married fair,
    Who'd give their lords to save their hair,
    No stellar recognition's given.
    There are not stars enough in heaven.
                                                                  G.J.