op = O = open source

open n.

Abbreviation for `open (or left) parenthesis' -- used when necessary to eliminate oral ambiguity. To read aloud the LISP form (DEFUN FOO (X) (PLUS X 1)) one might say: "Open defun foo, open eks close, open, plus eks one, close close."

--The Jargon File version 4.3.1, ed. ESR, autonoded by rescdsk.