[ kap-uh-lar-i-tee ]
/ ˌkæp əˈlær ɪ ti /


Also called capillary action, capillary attraction. Physics. a manifestation of surface tension by which the portion of the surface of a liquid coming in contact with a solid is elevated or depressed, depending on the adhesive or cohesive properties of the liquid.

Origin of capillarity

First recorded in 1820–30; capillary + -ty2
Related formsnon·cap·il·lar·i·ty, noun Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for capillary action


/ (ˌkæpɪˈlærɪtɪ) /


a phenomenon caused by surface tension and resulting in the distortion, elevation, or depression of the surface of a liquid in contact with a solidAlso called: capillary action
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

Medicine definitions for capillary action


[ kăp′ə-lărĭ-tē ]


The interaction between contacting surfaces of a liquid and a solid that distorts the liquid surface from a planar shape.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Science definitions for capillary action

capillary action

The movement of a liquid along the surface of a solid caused by the attraction of molecules of the liquid to the molecules of the solid.

A Closer Look

The paper towel industry owes its existence to capillary action, both for the way paper towels soak up liquids and for the trees out of which the towels are made. Molecules of water are naturally attracted to each other and form temporary hydrogen bonds with each other; their attraction for each other on the surface of a liquid, for example, gives rise to surface tension. But they are also attracted in a similar way to other molecules, called hydrophilic molecules, such as those in the sides of a narrow glass tube inserted into a cup of water, in the fibers of a towel, or in the cells of tree tissue known as xylem. These attractive forces can draw water upward against the force of gravity to a certain degree. However, they are not strong enough to draw water from the roots of a tree to its highest leaves. An additional, related force, referred to as transpiration pull, is required to do that. As water evaporates from the tiny pores, or stomata, of leaves, water from adjacent cells is drawn in to replace it by osmosis. Again, intermolecular attractive forces cause other water molecules to follow along, ultimately drawing water up from the roots of the tree.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.