1. n. [Drilling]

Tubular steel conduit fitted with special threaded ends called tool joints. The drillpipe connects the rig surface equipment with the bottomhole assembly and the bit, both to pump drilling fluid to the bit and to be able to raise, lower and rotate the bottomhole assembly and bit.

See: bottomhole assembly,  circulation system,  drilling fluid,  drillstem,  drillstring,  joint,  tool joint