noun
: a tube or rod of square cross section fitted into a square hole in the rotary-drill table and forming the top section of the rotary-drill shaft in an oil well
noun
: a tube or rod of square cross section fitted into a square hole in the rotary-drill table and forming the top section of the rotary-drill shaft in an oil well
Webster's New International English Dictionary. Новый международный словарь английского языка Webster. 2012