a tall machine used for moving or lifting heavy weights, especially on a ship; a type of crane 转臂起重机；（尤指船上的）吊杆式起重机 a tall structure over an oil well for holding the drill (= the machine that makes the hole in the ground for getting the oil out) （油井的）井架，钻塔
Word Originearly 17th cent. (denoting a hangman, also the gallows): from Derrick, the surname of a London hangman.