1. n. [Drilling]

The upside down V-shaped opening in one side of the derrick that enables long pipes and tools to be lifted into the interior of the derrick. This opening is aligned with the slide and catwalk of the rig.

See: catwalk,  mousehole,  racking back pipe,  slide,  slide

2. n. [Drilling]

The open location on a mast-type rig (nonderrick) that functions like the vee-door. At least two sides are open on most mast rigs. Hence, the open side adjacent to the slide and catwalk is considered the vee-door. The vee-door is really a hole and has no true door that can be closed or locked, so inexperienced visitors to a rigsite are sometimes asked by the rig crew to find the key to the vee-door as a joke.

See: mast