Noncompressible liquid: The fluid which does not show a change in volume or density when subjected to external forces.
Knurling: Knurling is a manufacturing process, typically conducted on a lathe, whereby a pattern of straight, angled or crossed lines is rolled into the material.
Factor of safety: In engineering, a factor of safety (FoS), also known as safety factor (SF), expresses how much stronger a system is than it needs to be for an intended load.
Otto cycle: An Otto cycle is an idealized thermodynamic cycle that describes the functioning of a typical spark ignition piston engine. The Otto cycle is a description of what happens to a mass of gas as it is subjected to changes of pressure, temperature, volume, addition of heat, and removal of heat.