an electronic device or software program that allows a sequence of musical sounds, recorded in digital form, to be altered before being played back
See sequencer in American Heritage Dictionary 4
(sēˈkwən-sər, -kwĕnˌ-)
noun
One that sequences, as:
a. An electronic device or software program that can be instructed to order and modify digitally stored musical sounds for playback, as through a synthesizer.
b. An apparatus for determining the order of constituents in a biological polymer, usually DNA or protein. In this sense also called sequenator.