intertropical convergence zonen. A broad area of low atmospheric pressure where the northeasterly and southeasterly trade winds converge over the equatorial region, extending approximately 10° north and south of the equator. Warm, humid air that converges here rises and cools, forming clouds and frequent, heavy showers.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.Intertropical Convergence Zone n (Physical Geography) meteorol the zone of deep convection and heavy rainfall in the tropics, esp along or near the equator. Abbreviation: ITCZ Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014