A phenomenon exhibited by an alternating-current circuit in which there are relatively large currents near certain frequencies, and a relatively unimpeded oscillation of energy from a potential to a kinetic form; a special case of the physics definition.

A feature of the valence-bond method that accounts for the anomalies in certain molecules by representing their structures with approximate resonance hybrid formulas; no single electronic formula conforms both to the observed properties and to the octet rule. Also known as mesomerism.

1. A phenomenon exhibited by a physical system acted upon by an external periodic driving force, in which the resulting amplitude of oscillation of the system becomes large when the frequency of the driving force approaches a natural free oscillation frequency of the system.

2. In general, any phenomenon which is greatly enhanced at frequencies or energies that are at or very close to a given characteristic value.

See <<resonance absorption>>, <<resonance level>>