plash (pl?sh)n.1. A light splash.2. The sound of a light splash.v. plashed, plash·ing, plash·es v.tr. To spatter (liquid) about; splash.v.intr. To cause a light splash.[Possibly from Middle English plashe, pool of water, from Old English plæsc.]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.