radiation pressure

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

• noun Force per unit area exerted by waves or particles of radiation, especially photons.

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

• noun physics The pressure exerted by electromagnetic radiation on an object on which it impinges, as a consequence of its momentum.

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

• noun the minute pressure exerted on a surface normal to the direction of propagation of a wave