“Rathole” or “mousehole” means the temporary storage space that is used to store the kelly or drill pipe while adding a new section of pipe to the drill string at some rotary drilling rigs.
Source: Division of Mineral Resources Management – Oil and Gas, Ohio Administrative Code, Chapter 1501:9, January 2012. Regulations
An opening through the rig floor, usually lined with pipe, into which a length of drill pipe is placed temporarily for later connection to the drill string.
Source: Petroleum Safety Orders–Drilling and Production, Definitions, California Code of Regulations, 8 CCR § 6505, December 2012. Regulations