a disk or cylindrical part tightly fitting and moving within a cylinder, either to compress or move a fluid collected in the cylinder, as air or water, or to transform energy imparted by a fluid entering or expanding inside the cylinder, as compressed air, explosive gases, or steam, into a rectilinear motion usually transformed into rotary motion by means of a connecting rod.
a pumplike valve used to change the pitch in a cornet or the like.
1695-1705; < French < Italianpistone piston, a learned alteration of pestone large pestle, equivalent to pest(are) to pound (variant of Medieval Latinpistare, derivative of Latinpīstus past participle of pīnsere to pound) + -one augmentative suffix
piston valve, for regulating fluids that carry solids in suspension.
It consists of a hammerlike piston located within a cylinder.
The two major types of valves are rotary valves and piston valves.
It is located in a cylinder and is made gastight by piston rings.
This means that the linear motion of a piston must be turned into a rotation.
British Dictionary definitions for piston
a disc or cylindrical part that slides to and fro in a hollow cylinder. In an internal-combustion engine it is forced to move by the expanding gases in the cylinder head and is attached by a pivoted connecting rod to a crankshaft or flywheel, thus converting reciprocating motion into rotation
C18: via French from Old Italian pistone, from pistare to pound, grind, from Latin pinsere to crush, beat
1704, from Fr. piston, from M.Fr. piston "large pestle," from O.It. pistone, variant of pestone "a pestle," from pestare "to pound," from L.L. pistare, freq. of L. pinsere (pp. pistus) "to pound" (see pestle).
A solid cylinder or disk that fits snugly into a hollow cylinder and moves back and forth under the pressure of a fluid (typically a hot gas formed by combustion, as in many engines), or moves or compresses a fluid, as in a pump or compressor.