cavitation definitions

Merriam Webster's

noun Etymology: cavity + -ation Date: 1895 the process of cavitating: as a. the formation of partial vacuums in a liquid by a swiftly moving solid body (as a propeller) or by high-intensity sound waves; also the pitting and wearing away of solid surfaces (as of metal or concrete) as a result of the collapse of these vacuums in surrounding liquid b. the formation of cavities in an organ or tissue especially in disease

Britannica Concise

Formation of vapor bubbles within a liquid at low-pressure regions that occur in places where the liquid has been accelerated to high velocities, as in the operation of centrifugal pumps, water turbines, and marine propellers. Cavitation is undesirable because it produces extensive erosion of the rotating blades, additional noise from the resultant knocking and vibrations, and a significant reduction of efficiency because it distorts the flow pattern. The cavities form when the pressure of the liquid has been reduced to its vapor pressure; they expand as the pressure is further reduced along with the flow, and they suddenly collapse when they reach regions of higher pressure.

Oxford Reference Dictionary

n. 1 the formation of a cavity in a structure. 2 the formation of bubbles, or of a vacuum, in a liquid.