tracker

/T R AE1 K ER0/
noun
  1. 1

    Agent noun of track; one who, or that which, tracks or pursues, as a man or dog that follows game.

  2. 2

    In an organ, a light strip of wood connecting (in path) a key and a pallet, to communicate motion by pulling.

  3. 3

    A type of computer software for composing music by aligning samples on parallel timelines.

  4. 4

    A musician who writes music in a tracker.

  5. 5

    A computer program that monitors something.

  6. 6

    A tracker mortgage.

Source: https://en.wiktionary.org/wiki/tracker