V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

MTU
       Maximum Transmission Unit (SLIP, PPP, IP, PPPoE)


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

MTU
       Message Transfer Unit


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

Maximum Transmission Unit
MTU

    (MTU) The largest number of bytes of "payload"
   data a frame can carry, not counting the frame's header
   and trailer.

   A frame is a single unit of transportation on the data link
   layer.  It consists of header data plus data which was passed
   down from the network layer (e.g. an IP datagram) plus
   sometimes trailer data.

   An Ethernet (V2) frame has a MTU of 1500 bytes but the size of
   the frame can be up to 1526 bytes (22 byte header, 4 byte CRC
   trailer).

   See also fragmentation.

   (2000-10-07)