The Collaborative International Dictionary of English v.0.48:

Derrick \Der"rick\, n. [Orig., a gallows, from a hangman named
   Derrick. The name is of Dutch origin; D. Diederik, Dierryk,
   prop. meaning, chief of the people; cf. AS. pe['o]dric, E.
   Theodoric, G. Dietrich. See Dutch, and Rich.]
   1. A mast, spar, or tall frame, supported at the top by stays
      or guys, and usually pivoted at the base, with suitable
      tackle for hoisting heavy weights, such as stones in
      building.
      [1913 Webster]

   2. (Mining) The pyramidal structure or tower over a deep
      drill hole, such as that of an oil well (also called an
      oil derrick .
      [Webster 1913 Suppl. +PJC]

   Derrick crane, a combination of the derrick and the crane,
      having facility for hoisting and also for swinging the
      load horizontally.
      [1913 Webster]

WordNet (r) 3.0 (2006):

derrick
    n 1: a framework erected over an oil well to allow drill tubes
         to be raised and lowered
    2: a simple crane having lifting tackle slung from a boom

Moby Thesaurus II by Grady Ward, 1.0:

53 Moby Thesaurus words for "derrick":
   antenna tower, barbican, belfry, bell tower, campanile, colossus,
   column, crab, crane, cupola, dome, erector, fire tower, forklift,
   gantry crane, hoist, hydraulic tailgate, jack, jackscrew, lantern,
   lever, lift, lifter, lighthouse, martello, martello tower, mast,
   minaret, monument, obelisk, observation tower, pagoda, pilaster,
   pillar, pinnacle, pole, pylon, pyramid, shaft, skyscraper, spire,
   standpipe, steeple, stupa, tackle, television mast, tope, tour,
   tower, turret, water tower, windlass, windmill tower