Glossary of Terms:
 
MIDI controller
A device that generates a MIDI signal to control synthesizers, sound modules or sample playback units. These devices include keyboard controllers, guitar controllers with a special pickup to convert signals from the strings into MIDI data, wind controllers which convert pitches blown into the unit into MIDI data, and drum controllers with rubber or mesh pads that can trigger MIDI note data.
Source:

Also refered as:
  controller
Related terms:
  MIDI   aftertouch   pressure sensitivity   synthesizer   touch sensitivity   velocity sensitivity