1.
Opposite
Prompt. British term for
Stage Right. See
Opposite Prompt, OP and
Prompt Side, PS. Since PS is (usually) Stage Left, OP is Stage Right.
2. Short for
Operator, as in Board Op,
Spot Op, Sound Op,
etc.
3.
Orchestra
Pit, see
Orchestra Pit.
4. In CB and other online forum parlance, may also stand for
Original
Poster--one who made a statement, as in "The OP said...", or
Original
Post.