A radical change in thinking from an accepted point of view to a new one, necessitated when new scientific discoveries produce anomalies in the current paradigm.

(physics) a small difference in the transition energies of isotopes that corresponds to a given spectral line transition

(chemistry, physics) The change in the nuclear magnetic resonance frequency of a nucleus depending on its electronic environment; used in NMR spectroscopy to determine the structure of molecules.

The key on a typewriter used to select uppercase letters and certain special characters by physically moving the mechanism

(historical, US, automotive) An early mechanism that synchronized the speeds of gear wheels when changing gear in an automobile.

(automotive) That part of a gearbox involved in changing gear, including the lever and the forks attached to it. / (automotive, US, Canada) The lever or other interface a human uses to shift gears.

(US) A work shift between a day shift and a night shift, such as from 4PM to midnight, and the group of workers scheduled to work such a shift at a facility.

a work shift that covers late evening and early morning hours.

A type of work cycle, most commonly at a manufacturing plant or institution, with shifts worked four days in a row, followed by four days off in a row. It can also commonly be implemented as working four days in a row with three days off, then working three days in a row with four days off; switching every week.

The Doppler effect.