any body or system that displays resonance, esp a tuned electrical circuit or a conducting cavity in which microwaves are generated by a resonant current
resonator in American English
(ˈrɛzəˌneɪtər)
noun
1.
a device for producing resonance or increasing sound by resonance
2. Electronics
an apparatus or system, as a piezoelectric crystal or a circuit, capable of being put into oscillation by oscillations in another system