1. (n.) One who, or that which, multiplies or increases number.

2. (n.) The number by which another number is multiplied.

3. (n.) An instrument for multiplying or increasing by repetition or accumulation the intensity of a force or action, as heat or electricity. It is particularly used to render such a force or action appreciable or measurable when feeble. See Thermomultiplier.

attenuator audio-frequency tube ballast regulator ballast tube beam-switching tube convertor current regulator damper detector discriminator doubler ear trumpet electronic hearing aid focus tube generator hard-of-hearing aid hearing aid iconoscope inverter limiter local-oscillator tube megaphone mixer tube modulator multiplier multipurpose tube multivibrator oscillator output tube phase inverter picture tube power tube preamp preamplifier pulse generator radio-frequency tube receiving tube rectifier tube regulator repeater speaking trumpet stethoscope transducer transistor hearing aid trigger tube vacuum-tube hearing aid