• A tuner is a device to adjust the resonant frequency of an antenna or transmission line to work most efficiently at one frequency or band of frequencies.
• A tuner is a radio receiver without an amplifier or loudspeaker, which is often constructed for superior audio quality in high fidelity applications, as in FM tuner.
• A tuner is a professional who adjusts the pitch of musical string instruments such as pianos using a tuning fork, or a frequency counter electronic device using a quartz crystal, as a frequency reference.

de:Tuner nl:Tuner ja:チューナー