1 the reinforcement or prolongation of sound by reflection or synchronous vibration.
2 Mech. a condition in which an object or system is subjected to an oscillating force having a frequency close to its own natural frequency.
3 Chem. the property of a molecule having a structure best represented by two or more forms rather than a single structural formula.
4 Physics a short-lived elementary particle that is an excited state of a more stable particle.
Etymology: OF f. L resonantia echo (as RESONANT)
Useful english dictionary. 2012.