Inby and outby are directional terms in underground mining. Inby refers to the direction that is toward the coal or ore face. Outby refers to the direction that is away from the coal or ore face.

These terms can be used in describing where something in the mine is located or how something is oriented.

For example, consider a situation where a crew member is looking for a section foreman. Another crew member may offer "I saw him headed inby 15 minutes ago." This means that the forman was moving toward the working face.