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

back quote
backtick

    "`" ASCII code 96.  Common names: left quote;
   left single quote; open quote; ITU-T: grave accent; grave.
   Rare: backprime; INTERCAL: backspark; unapostrophe; birk;
   blugle; back tick; back glitch; push; ITU-T: opening single
   quotation mark; quasiquote.

   Back quote is used in Unix shells to invoke command
   substitution.

   (1996-11-26)