Gravimetric shear, also known as "grav shear" or "spatial turbulence," is a type of gravimetric distortion and a shear force commonly associated with certain astronomical phenomena such as stellar clusters and neutronic storms, that can pose a threat to starships. Shear is caused by localized, extreme differences in the gravitational coefficient that produces great stress on matter that crosses the point of localized difference. Enterprise NX-01 encountered severe grav shear in 2152 when it passed through a class five neutronic storm. (ENT: "The Catwalk")