1. Plumbing. Where the water comes out.
2a. Lighting. Piece of attachment hardware commonly found on studio lighting fixtures to provide a wider range of mounting options than the theatrical C-Clamp.
2b. May also (loosely) refer to the part of a theatrical c-clamp that the yoke bolt threads into.
3. Rigging. An alternative truss end design to bolt plates, the "fork and spigot" is arguably faster and stronger.