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[lak-uh-lith] /ˈlæk ə lɪθ/
noun, Geology
a mass of igneous rock formed from magma that did not find its way to the surface but spread laterally into a lenticular body, forcing overlying strata to bulge upward.
Also, laccolite
[lak-uh-lahyt] /ˈlæk əˌlaɪt/ (Show IPA)
1875-80; < Greek lákko(s) pond + -lith
Related forms
laccolithic, laccolitic
[lak-uh-lit-ik] /ˌlæk əˈlɪt ɪk/ (Show IPA),
adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for laccolith
  • The hardened magma that forms this type of dome is called laccolith.
  • The range is an exposed laccolith, but the lake is in the area of uplifted sedimentary rocks rather than exposed igneous rocks.
  • At the extreme right the sedimentary rocks are upturned on the flanks of the laccolith.
British Dictionary definitions for laccolith


a dome-shaped body of igneous rock between two layers of older sedimentary rock: formed by the intrusion of magma, forcing the overlying strata into the shape of a dome See lopolith
Derived Forms
laccolithic, laccolitic (ˌlækəˈlɪtɪk) adjective
Word Origin
C19: from Greek lakkos cistern + -lith
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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laccolith in Science
A body of igneous rock intruded between layers of sedimentary rock, resulting in uplift. Laccoliths are usually plano-convex in cross-section, having a flat bottom and a convex top, and are roughly circular in plan. They are usually connected to a dike and are typically up to 8 km (5 mi) in diameter and tens to hundreds of meters thick. See illustration at batholith.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Encyclopedia Article for laccolith

in geology, any of a type of igneous intrusion that has split apart two strata, resulting in a domelike structure; the floor of the structure is usually horizontal. A laccolith is often smaller than a stock, which is another type of igneous intrusion, and usually is less than 16 km (10 miles) in diameter; the thickness of laccoliths ranges from hundreds of metres to a few thousand metres. They can be contrasted with sills, which are sheetlike intrusions oriented parallel to the bedding of the enclosing rock: a laccolith's ratio of diameter to thickness should be less than 10; a larger ratio would make the body a sill. Acidic rocks are more common than basic rocks in laccoliths. Although the lower portions of laccoliths are seldom visible, they usually are interpreted as having a relatively small feeder from a magma source below. A well-known example of a laccolith is found in the Henry Mountains, Utah.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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