n. [ F. bivalve; bi- (L. bis) + valve valve. ] 1. (Zool.) A mollusk having a shell consisting of two lateral plates or valves joined together by an elastic ligament at the hinge, which is usually strengthened by prominences called teeth. The shell is closed by the contraction of two transverse muscles attached to the inner surface, as in the clam, -- or by one, as in the oyster. See Mollusca. [ 1913 Webster ]

2. (Bot.) A pericarp in which the seed case opens or splits into two parts or valves. [ 1913 Webster ]

a. [ Pref. bi- + valve. ] (Zool. & Bot.) Having two shells or valves which open and shut, as the oyster and certain seed vessels. [ 1913 Webster ]

a. Having two valves, as the oyster and some seed pods; bivalve. [ 1913 Webster ]

(Mach.) See Snifting valve. [ 1913 Webster ]

See under Valve. [ 1913 Webster ]

(Mech.) A kind of slide valve. See Slide valve, under Slide. [ 1913 Webster ]

{ } a. [ Equi- + valve. ] (Zoöl.) Having the valves equal in size and from, as in most bivalve shells. [ 1913 Webster ]

. (Mech.) A suction valve or check valve at the lower end of a pipe; esp., such a valve in a steam-engine condenser opening to the air pump. [ Webster 1913 Suppl. ]

{ } a. (Zool.) Having unequal valves, as the shell of an oyster. [ 1913 Webster ]

pos>n. (Marine Steam Engin.) A conical valve, opening outward, to close the mouth of a pipe which passes through the side of a vessel below the water line. [ 1913 Webster ]

n. [ Cf. F. multivalve. ] (Zool.) Any mollusk which has a shell composed of more than two pieces. [ 1913 Webster ]

{ } a. [ Multi- + valve, valvular: cf. F. multivalve. ] 1. Having many valves. [ 1913 Webster ]

2. (Zool.) Many-valved; having more than two valves; -- said of certain shells, as the chitons. [ 1913 Webster ]

. (Hydraulics) A small hand-operated valve to admit liquid to operate a valve difficult to turn by hand. [ Webster 1913 Suppl. ]

a. [ Quadri- + valve: cf. F. quadrivalve. ] (Bot.) Dehiscent into four similar parts; four-valved; as, a quadrivalve pericarp. [ 1913 Webster ]

n. (Arch.) A door, shutter, or the like, having four folds. [ 1913 Webster ]

{ } a. [ Quinque- + valve, valvular: cf. F. quinquévalve. ] (Bot.) Having five valves, as a pericarp. [ 1913 Webster ]

. (Mach.) A valve permitting a fluid under pressure an easier avenue of escape than normally; specif., a valve, actuated by the governor, used in one system of marine-engine governing to connect both ends of the low-pressure cylinder as a supplementary control. [ Webster 1913 Suppl. ]

a. Consisting of, or having, three valves; opening with three valves; as, a three-valved pericarp. [ 1913 Webster ]

n. [ Pref. tri- + valve. ] Anything having three valves, especially a shell. [ 1913 Webster ]

n. [ See Tube, Valve. ] (Zool.) A shell or tube formed by an annelid, as a serpula. [ 1913 Webster ]

n. [ Uni- + valve: cf. F. univalve. ] (Zool.) A shell consisting of one valve only; a mollusk whose shell is composed of a single piece, as the snails and conchs. [ 1913 Webster ]

☞ Most univalves are spiral and are the shells of gastropods, but many belong to cephalopods and pteropods. A large number of univalves belonging to the gastropods are conical, cup-shaped, or shieldlike, as the limpets. [ 1913 Webster ]

{ } a. [ Cf. F. univalve. ] (Bot. & Zool.) Having one valve; as, a univalve shell or pericarp. [ 1913 Webster ]

n. [ L. valva the leaf, fold, or valve of a door: cf. F. valve. ] [ 1913 Webster ]

1. A door; especially, one of a pair of folding doors, or one of the leaves of such a door. [ 1913 Webster ]

Swift through the valves the visionary fair
Repassed. Pope. [ 1913 Webster ]

Heavily closed, . . . the valves of the barn doors. Longfellow. [ 1913 Webster ]

2. A lid, plug, or cover, applied to an aperture so that by its movement, as by swinging, lifting and falling, sliding, turning, or the like, it will open or close the aperture to permit or prevent passage, as of a fluid. [ 1913 Webster ]

☞ A valve may act automatically so as to be opened by the effort of a fluid to pass in one direction, and closed by the effort to pass in the other direction, as a clack valve; or it may be opened or closed by hand or by mechanism, as a screw valve, or a slide valve. [ 1913 Webster ]

3. (Anat.) One or more membranous partitions, flaps, or folds, which permit the passage of the contents of a vessel or cavity in one direction, but stop or retard the flow in the opposite direction; as, the ileocolic, mitral, and semilunar valves. [ 1913 Webster ]

4. (Bot.) (a) One of the pieces into which a capsule naturally separates when it bursts. (b) One of the two similar portions of the shell of a diatom. (c) A small portion of certain anthers, which opens like a trapdoor to allow the pollen to escape, as in the barberry. [ 1913 Webster ]

5. (Zool.) One of the pieces or divisions of bivalve or multivalve shells. [ 1913 Webster ]

Air valve,
Ball valve,
Check valve, etc. See under Air. Ball, Check, etc. --
Double-beat valve, a kind of balance valve usually consisting of a movable, open-ended, turban-shaped shell provided with two faces of nearly equal diameters, one above another, which rest upon two corresponding seats when the valve is closed. --
Equilibrium valve. (a) A balance valve. See under Balance. (b) A valve for permitting air, steam, water, etc., to pass into or out of a chamber so as to establish or maintain equal pressure within and without. --
Valve chest (Mach.), a chamber in which a valve works; especially (Steam Engine), the steam chest; -- called in England valve box, and valve casing. See Steam chest, under Steam. --
Valve face (Mach.), that part of the surface of a valve which comes in contact with the valve seat. --
Valve gear, or
Valve motion (Steam Engine), the system of parts by which motion is given to the valve or valves for the distribution of steam in the cylinder. For an illustration of one form of valve gear, see Link motion. --
Valve seat. (Mach.) (a) The fixed surface on which a valve rests or against which it presses. (b) A part or piece on which such a surface is formed. --
Valve stem (Mach.), a rod attached to a valve, for moving it. --
Valve yoke (Mach.), a strap embracing a slide valve and connecting it to the valve stem. [ 1913 Webster ]

a. Having a valve or valves; valvate. [ 1913 Webster ]

n. A little valve; a valvule; especially, one of the pieces which compose the outer covering of a pericarp. [ 1913 Webster ]

n. (Zool.) Any fresh-water gastropod of the genus Valvata. [ 1913 Webster ]