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

left parenthesis
(
open parenthesis

    "(".  ASCII character 40.

   Common names: left paren; left parenthesis; left; open;
   paren (")" = thesis); open paren; open parenthesis; left
   parenthesis; left banana.  Rare: so (")" = already); lparen;
   ITU-T: opening parenthesis; open round bracket, left round
   bracket, INTERCAL: wax (")" = wane); parenthisey (")" =
   unparenthisey); left ear.

   Paired with right parenthesis (")").

   (1995-03-06)