stillson wrench

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

• A pipe wrench having an adjustable L-shaped jaw piece sliding in a sleeve that is pivoted to, and loosely embraces, the handle. Pressure on the handle increases the grip.

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

• noun a large pipe wrench with L-shaped adjustable jaws that tighten as pressure on the handle is increased