velum

n. membranous covering (such as the soft palate); veil, thin membrane which covers an immature mushroom

The term, velum, derived from Latin velum, meaning a "sail", "curtain," "awning" or "veil", has several quite separate meanings in biology:the locomotory and feeding organ provided with cilia found in the larval stage called the veliger or "velum-bearing" stage of bivalves, such as mussels and oysters; also a delicate membrane found on certain Protists. the circular membrane round the cap of a sea jelly or medusa of class Hydrozoa the veil-like membrane of immature mushrooms extending from the margin of the cap to the stem and torn by growth, revealing the gills of a mature sporophore; in a mature mushroom, the remains of the velum may form an annulus or ring around the stem, familiar from common button mushrooms and sometimes on the margin of the cap. the soft palate behind the hard palate the superior medullary velumVelum is also a common misspelling of vellum, calfskin (or sometimes the skins of other animals) that is similar to parchment and that is used as medium for writing, book printing, and book binding. Today, Leatherette, leather, cloth or paper are more commonly used, but vellum is still used occasionally.
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Noun
1. membrane of the young sporophore of various mushrooms extending from the margin of the cap to the stem and is ruptured by growth; represented in mature mushroom by an annulus around the stem and sometimes a cortina on the margin of the cap
(synonym) partial veil
(hypernym) plant part, plant structure
(hyponym) cortina
(part-meronym) annulus
2. membrane initially completely investing the young sporophore of various mushrooms that is ruptured by growth; represented in the mature mushroom by a volva around lower part of stem and scales on upper surface of the cap
(synonym) universal veil
(hypernym) plant part, plant structure
3. a muscular flap that closes off the nasopharynx during swallowing or speaking
(synonym) soft palate
(hypernym) flap
(part-holonym) palate, roof of the mouth
(part-meronym) uvula

n. velum

n. canopy, covering

(n.)
The circular membrane that partially incloses the space beneath the umbrella of hydroid medusae.
  

(n.)
See Veil, n., 3 (b).
  

(n.)
Curtain or covering; -- applied to various membranous partitions, especially to the soft palate. See under Palate.
  

(n.)
A veil-like organ or part.
  

(n.)
A thin membrane surrounding the sporocarps of quillworts Isoetes).
  

(n.)
A delicate funnel-like membrane around the flagellum of certain Infusoria. See Illust. a of Protozoa.