tracker

noun10

1. •
   Agent noun of track; one who, or that which, tracks or pursues, as a man or dog that follows game.
2. •
   (US) A person employed to follow and monitor a political rival.
3. •
   (Australia) An Indigenous Australian employed by the law to track down fugitives and missing persons.

   • The police picked him up, reared him, and he had been a tracker ever since, except for periodical walk-abouts. — 1937
4. •
   A computer program that monitors something.
5. •
   Server software that coordinates peers in the BitTorrent protocol.
6. •
   [in compounds] An album with the specified number of tracks.

   • "Typical" is the best song on this nine-tracker, and ironically, the record itself is good, but typical. — 1985
7. •
   A type of computer software for composing music by aligning notes or samples on parallel timelines.

   • Although there were a few game companies outside the Amiga scene that used a tracker format (Epic Mega-Games, for instance), the majority used the better-supported MIDI. — 2008
8. •
   A tracker mortgage.
9. •
   A musician who writes music in a tracker.

   • You can always find musicians. There are more trackers than coders, pixelers, organizers, couriers, and designers combined. — 1999
10. •
    In an organ, a light strip of wood connecting (in path) a key and a pallet, to communicate motion by pulling.