Probably the single word with the most definitions in all of theatre. Trim can mean/refer to:
1. The height of a suspended (flown) scenic piece.
1a. The level or plumb of an object. "Second Electric is not at trim" means something different than "Second Electric is out of trim."
2. To cut away a small portion of material: cloth, wood, metal, plastic, hair. "Trim the wicks" (on candles; (my first job in the theatre)).
2a. To speed up time: "We need to trim the Second Act, it's running too long."
3. The "frilly" stuff (lace, rick-rack, fringe, etc.) on a costume, drapery, or hat.
4. The distance between electrodes of a carbon-arc light source. "Spot2 is out of trim."
4a. A set of the carbons themselves. "Spot2 needs to retrim."
5. Physically fit, slender.
6. To adorn, "Trim the Christmas tree."
7. To adjust, "Trim the sails on a boat," (from where most of our rigging terms come).
8. The calibration of an analog dimmer.
9. Attenuation, as in the "trim pots" on a sound board.
Others I forgot?