The Free On-line Dictionary of Computing (30 December 2018):

TrackPoint
pointing stick

    (Or "pointing stick", "nipple") A small knob found
   in the middle of some keyboards that works like a very short
   isometric joystick.  Pressing it toward or away from you or
   from side to side moves the pointer on the screen.  Ted
   Selker brought the concept of an in-keyboard pointing device
   to IBM in September 1987.  TrackPoint was introduced in 1992
   on the IBM ThinkPad and later on some desktops.

   It takes up virtually no extra room on the box or the work
   area and also requires minimal movement of the hands from the
   keyboard.

   Many imitations of highly variable quality appeared.  Pointing
   sticks have also been used in many other notebook brands,
   including TI, HP, Compac, Dell, Toshiba
   (e.g. Portege 4000's "AccuPoint II"), and AST (e.g. Ascentia
   910N).

   "TrackPoint" and "Trackpoint" are IBM trademarks.

   (http://research.ibm.com/mathsci/cmc/trackpoint.htm).

   [INTERACT'90, North Holland Pub Co, pp. 700-706].

   (2003-10-15)