From The Collaborative International Dictionary of English v.0.48 [gcide]:
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]
From WordNet (r) 3.0 (2006) [wn]:
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