1) blowout preventer stack 2) blowout preventer 3) blow-out preventer stack 4) blow-out preventer an equipment installed at an oil wellhead for the purpose of controlling pressures in the annular space between the casing and drill pipe, or in an open hole during drilling operations
BOP GRM: n. (1,2,3,4) Note: usually hydraulically operated, fitted to the top of casing series of a drilling well to prevent a (gas) blowout