The Collaborative International Dictionary of English v.0.48:

backspace \backspace\, backspacer \backspacer\n.
   1. The key on a typewriter or other keyboard used for back
      spacing.

   Syn: backspace key.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

backspace \backspace\, v. i.
   In typing text, to press the backspace key so as to
   reposition the carriage or cursor on the previous space.
   [PJC]

WordNet (r) 3.0 (2006):

backspace
    n 1: the typewriter key used for back spacing [syn: backspace
         key, backspace, backspacer]
    v 1: hit the backspace key on a computer or typewriter keyboard;
         "To erase, you must backspace"

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

backspace
BS

    (BS) ASCII code 8, Control-H.  The control
   character that should cause most output devices to move
   their current output position back to the previous character
   so that the next character output will replace (or overprint)
   it.  Inputting a backspace (typically by pressing the
   backspace key) causes many systems to delete the character
   before the input cursor, though others use delete for this.

   See twirling baton for an imaginitive use of backspace.

   (2003-10-25)