Valve vs. Stopcock — What's the Difference?

A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fittings, but are usually discussed as a separate category.

A stopcock is a form of valve used to control the flow of a liquid or gas. The term is not precise and is applied to many different types of valve.

A device for controlling the passage of fluid or air through a pipe, duct, etc., especially an automatic device allowing movement in one direction only

An externally operated valve regulating the flow of a liquid or gas through a pipe, in particular one on the water main supplying a house

Each of the halves of the hinged shell of a bivalve mollusc or brachiopod, or of the parts of the compound shell of a barnacle.

A valve that regulates the flow of fluid through a pipe; a faucet.

Any of various devices that regulate the flow of gases, liquids, or loose materials through piping or through apertures by opening, closing, or obstructing ports or passageways.

A valve, tap or faucet which regulates the flow of liquid or gas through a pipe.

The movable control element of such a device.

(British) A main shutoff#Noun for water to a home from a municipal supply. Usually these valves exist in pairs, one outside the property boundary and one inside the property boundary.

A device in a brass wind instrument that can be opened or closed to change the pitch by altering the length of the air column in the tube.

(transitive) To control the gas pressure in (an oil well) by keeping the well closed in and the gas confined except during set intervals when the oil is flowed or pumped.

(Anatomy) A membranous structure in a hollow organ or passage, as in an artery or vein, that folds or closes to prevent the return flow of the body fluid passing through it.

A bib, faucet, or short pipe, fitted with a turning stopper or plug for permitting or restraining the flow of a liquid or gas; a cock or valve for checking or regulating the flow of water, gas, etc., through or from a pipe, etc.

A piece of shell covering or enclosing certain mollusks or other invertebrates, especially the single one of a univalve mollusk or one of the paired hinged ones of a bivalve mollusk or brachiopod.

The turning plug, stopper, or spigot of a faucet.

One of the two siliceous halves of the cell wall of a diatom.

Faucet consisting of a rotating device for regulating flow of a liquid

One of the pieces into which a plant part splits at maturity, especially a segment of a fruit capsule or of certain anthers.

Chiefly British An electron tube or a vacuum tube.

(Archaic) Either half of a double or folding door.

To provide with a valve.

To control by means of a valve.

A device that controls the flow of a gas or fluid through a pipe.

A device that admits fuel and air into the cylinder of an internal combustion engine, or one that allows combustion gases to exit.

(anatomy) 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 control the flow in the opposite direction

One of the leaves of a folding-door, or a window-sash.

(British) A vacuum tube.

(botany) One of the pieces into which certain fruits naturally separate when they dehisce.

(botany) A small portion of certain anthers, which opens like a trapdoor to allow the pollen to escape, such as in the barberry.

(biology) One of the pieces or divisions of bivalve or multivalve shells.

(biology) One of the two similar portions of the shell of a diatom.

(transitive) To control (flow) by means of a valve.

A door; especially, one of a pair of folding doors, or one of the leaves of such a door.

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.

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.

One of the pieces into which a capsule naturally separates when it bursts.

One of the pieces or divisions of bivalve or multivalve shells.

A structure in a hollow organ (like the heart) with a flap to insure one-way flow of fluid through it

Device in a brass wind instrument for varying the length of the air column to alter the pitch of a tone

Control consisting of a mechanical device for controlling the flow of a fluid