Pronunciation: (der'ik),[key] —n. 1. Mach.a jib crane having a boom hinged near the base of the mast so as to rotate about the mast, for moving a load toward or away from the mast by raising or lowering the boom.
2. Also called oil derrick. the towerlike framework over an oil well or the like.
3. a boom for lifting cargo, pivoted at its inner end to a ship's mast or kingpost, and raised and supported at its outer end by topping lifts.