ˈvalv, ˈvau̇v noun
( -s )
Usage: often attributive
Etymology: Latin valva leaf of a folding or double door; akin to Latin volvere to roll, turn around — more at voluble
1.
a. archaic : a leaf or a half of a folding or double door
b. : the door or gate used for regulating the flow of water in a sluice
2. : something resembling or suggestive of a valve or stop especially in regulating, checking, or permitting flow or movement through a passage: as
a.
[New Latin valva ]
: any of various bodily structures especially in the veins and lymphatics whose function is to close temporarily a passage or orifice or permit a movement of fluid in one direction only and that may consist of a sphincter muscle or of two or sometimes three membranous folds inclined in the normal direction of flow — see mitral valve , semilunar valve , tricuspid valve
b.
(1) : any of numerous mechanical devices by which the flow of liquid, air or other gas, or loose material in bulk may be started, stopped, or regulated by a movable part that opens, shuts, or partially obstructs one or more ports or passageways ; also : the movable part of such a device — compare cock 2; see check valve , gate valve , piston valve , safety valve
(2) : such a device in a brass wind instrument that is designed for quickly varying the tube length in order to change the fundamental tone by some definite interval and usually consists of a piston or rotary valve
c. chiefly Britain : electron tube , vacuum tube
3.
[New Latin valva ]
a. : one of the distinct and usually movably articulated pieces of which the shell of lamellibranch mollusks, brachiopods, barnacles, and some other shell-bearing animals consists
b. : one of the pieces forming the sheath of the ovipositor or external genital organs of many insects
4.
[New Latin valva ]
a. : one of the segments or pieces into which a dehiscing capsule or legume separates
b. : the portion of various anthers (as of the barberry) resembling a lid
c. : one of the two silicified shells or encasing membranes of a diatom
5. : one of the two halves of a stone or clay mold used by primitive or ancient peoples for casting bronze objects