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intr.v. ker·plunked, ker·plunk·ing, ker·plunks
To fall with a sound like that of a heavy object falling into water.
A kerplunking sound or movement.
[ker-, intensive pref. (probably from Scots) + plunk.]
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.
1. informal a sound of something landing noisily
2. old-fashioned slang US an unexpected disappointment
to make a noise when landing on or hitting the bottom of something
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
with or as if with a sudden muffled thud: The rock hit the water kerplunk.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.