"(". 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 (")").