The Collaborative International Dictionary of English v.0.48:

Veil \Veil\ (v[=a]l), n. [OE. veile, OF. veile, F. voile, L.
   velum a sail, covering, curtain, veil, probably fr. vehere to
   bear, carry, and thus originally, that which bears the ship
   on. See Vehicle, and cf. Reveal.] [Written also vail.]
   [1913 Webster]
   1. Something hung up, or spread out, to intercept the view,
      and hide an object; a cover; a curtain; esp., a screen,
      usually of gauze, crape, or similar diaphnous material, to
      hide or protect the face.
      [1913 Webster]

            The veil of the temple was rent in twain. --Matt.
                                                  xxvii. 51.
      [1913 Webster]

            She, as a veil down to the slender waist,
            Her unadorn['e]d golden tresses wore. --Milton.
      [1913 Webster]

   2. A cover; a disguise; a mask; a pretense.
      [1913 Webster]

            [I will] pluck the borrowed veil of modesty from the
            so seeming Mistress Page.             --Shak.
      [1913 Webster]

   3. (Bot.)
      (a) The calyptra of mosses.
      (b) A membrane connecting the margin of the pileus of a
          mushroom with the stalk; -- called also velum.
          [1913 Webster]

   4. (Eccl.) A covering for a person or thing; as, a nun's
      veil; a paten veil; an altar veil.
      [1913 Webster]

   5. (Zool.) Same as Velum, 3.
      [1913 Webster]

   To take the veil (Eccl.), to receive or be covered with, a
      veil, as a nun, in token of retirement from the world; to
      become a nun.
      [1913 Webster]

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):

velum
    n 1: a membranous covering attached to the immature fruiting
         body of certain mushrooms [syn: veil, velum]
    2: a muscular flap that closes off the nasopharynx during
       swallowing or speaking [syn: soft palate, velum]