sundiv sagedus, mis võrdub süsteemi omavõnkesagedusega, sagedus, millel langevad kokku süsteemi vabavõnkumise sagedus ja välismõju sagedus ning tekib süsteemi võnkeamplituudi järsk kasv, in a cavity resonator the real part of the natural frequency of a particular mode of resonance, lower of the two frequencies of a piezoelectric resonator vibrating alone under specified conditions, at which the electrical impedance of the resonator is resistive, frequencies at which the response amplitude is a relative maximum are also known as resonant frequencies or resonance frequencies of the system