synthesizer
An electronic device that produces a variety of sounds. A synthesizer typically offers a preset range of different "patches", but as distinct from other types of portable keyboard instruments, it also allows the user to heavily edit the parameters of these sounds or even import/create entirely new sounds. As such, one almost always finds a densely populated control panel in addition to pitch and modulation wheels (see Yamaha, Kurzweil, Clavia Nord) or combination X-Y joystick (see Roland, Korg).
The common synthesizer has a keyboard similar to that of a piano, leading it to be sometimes called keyboard.
See also
This tag implicates instrument (learn more).