The Collaborative International Dictionary of English v.0.48:

Velum \Ve"lum\, n.; pl. Vela. [L., an awning, a veil. See
   Veil.]
   [1913 Webster]
   1. (Anat.) A curtain or covering; -- applied to various
      membranous partitions, especially to the soft palate. See
      under Palate.
      [1913 Webster]

   2. (Bot.)
      (a) See Veil, n., 3
      (b) .
      (b) A thin membrane surrounding the sporocarps of
          quillworts Isoetes).
          [1913 Webster]

   3. (Zool.) A veil-like organ or part. Especially:
      (a) The circular membrane that partially incloses the
          space beneath the umbrella of hydroid medusae.
      (b) A delicate funnel-like membrane around the flagellum
          of certain Infusoria. See Illust. a of Protozoa.
          [1913 Webster]

WordNet (r) 3.0 (2006):

Vela
    n 1: a constellation in the southern hemisphere between Carina
         and Pyxis; "because of its configuration Vela is sometimes
         called `the Sails'"