Acoustic quieting is the process of making machinery quieter by damping vibrations to prevent them from reaching the observer.
Acoustic signature is used to describe a combination of acoustic emissions of sound emitters, such as those of ships and submarines.
A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races.
Cavitation is the formation of vapour cavities in a liquid, small liquid-free zones ("bubbles" or "voids"), that are the consequence of forces acting upon the liquid.
A nuclear submarine is a submarine powered by a nuclear reactor.
A plain bearing, or more commonly sliding bearing and slide bearing (in railroading sometimes called a solid bearing or friction bearing), is the simplest type of bearing, comprising just a bearing surface and no rolling elements.
Sonar (originally an acronym for SOund Navigation And Ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, communicate with or detect objects on or under the surface of the water, such as other vessels.
Stealth technology also termed low observable technology (LO technology) is a sub-discipline of military tactics and passive electronic countermeasures, which cover a range of techniques used with personnel, aircraft, ships, submarines, missiles and satellites to make them less visible (ideally invisible) to radar, infrared, sonar and other detection methods.
A submarine (or simply sub) is a watercraft capable of independent operation underwater.