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

field effect transistor

    (FET) A transistor with a region of donor
   material with two terminals called the "source" and the
   "drain", and an adjoining region of acceptor material
   between, called the "gate".  The voltage between the gate and
   the substrate controls the current flow between source and
   drain by depleting the donor region of its charge carriers to
   greater or lesser extent.

   There are two kinds of FET's, Junction FETs and MOSFETs.

   Because no current (except a minute leakage current) flows
   through the gate, FETs can be used to make circuits with very
   low power consumption.

   Contrast bipolar transistor.

   (1995-10-05)