(physics) the resonant and recoil-free emission and absorption of gamma rays by atoms in the solid state; the basis of a type of spectroscopy with applications in both physics and chemistry

(physics) The splitting of single spectral lines into three (or more) in the presence of a magnetic field.

(physics) the magnetic self-attraction of parallel electric currents having the same direction; the restriction of a flowing plasma because of this attraction

(physics) the inelastic scattering of photons with subsequent change in frequency and phase; employed in Raman spectroscopy

(physics) the splitting and shift of a spectral line into several components in the presence of an electric field

(sociology) the observation that people often do or believe what they think many other people do.

(physics) The generation of an electric current in an intermetallic semiconductor in a magnetic field by the action of light.

(physics) The emission of electrons from the surface of a material following the absorption of electromagnetic radiation.

An artificially created or enhanced sound, used to accompany the action of a dramatic production, such as a film, play or video game

(ecology) The negative population growth observed at low population densities.