The Jargon File (version 4.4.7, 29 Dec 2003):

dumb terminal
 n.

    A terminal that is one step above a glass tty, having a minimally
    addressable cursor but no on-screen editing or other features normally
    supported by a smart terminal. Once upon a time, when glass ttys were
    common and addressable cursors were something special, what is now called a
    dumb terminal could pass for a smart terminal.


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

dumb terminal

    A type of terminal that consists of a keyboard
   and a display screen that can be used to enter and transmit
   data to, or display data from, a computer to which it is
   connected.  A dumb terminal, in contrast to an intelligent
   terminal, has no independent processing capability or
   auxiliary storage and thus cannot function as a stand-alone
   device.

   The dumbest kind of terminal is a glass tty.  The next step
   up has a minimally addressable cursor but no on-screen
   editing or other features normally supported by an
   intelligent terminal.

   Once upon a time, when glass ttys were common and addressable
   cursors were something special, what is now called a dumb
   terminal could pass for a smart terminal.

   [Examples?]

   [Jargon File]

   (1995-04-14)