iron maiden

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A medieval instrument of torture consisting of an iron frame in the form of a person in which the victim was enclosed and impaled on interior spikes.

from the GNU version of the Collaborative International Dictionary of English.

• noun An instrument of torture used in the middle ages, consisting of a box large enough to hold a person, often in the shape of a woman, and having multiple sharp spikes on the inside. Called also the iron maiden of Nuremberg.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun idiomatic, archaic A medieval torture device consisting of a chamber lined with spikes which encloses upon and impales the victim inside.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun instrument of torture consisting of a hollow iron frame shaped like the human body and lined with spikes to impale the victim