1. vb. [Drilling]

To take apart, disassemble and otherwise prepare to move the rig or blowout preventers.

See related terms: blowout preventer,  rig

2. n. [Well Completions]

The process of disassembling well-control or pressure-control equipment on the wellhead. Depending on the configuration of the wellhead and casing strings, it may be necessary to nipple-down and nipple-up the blowout preventer (BOP) system as each casing string is run.

Antonyms: nipple up,  nipple-up

See related terms: blowout preventer,  casing string