zonk (zôngk, z?ngk)v. zonked, zonk·ing, zonks Slang v.tr.1. To cause to be asleep. Often used with out: My roommate was zonked out on the couch.2. To stupefy or intoxicate with drugs or alcohol: “zonk their patients with tranquilizers” (Psychology Today).v.intr.1. To go to sleep or be asleep. Often used with out.2. To become intoxicated with drugs or alcohol.[Origin unknown.]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.zonk (z??k) vb (tr) to strike resoundingly or hit heavilyCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014zonk (z??k, z??k) Slang. v.i. 1. to become stupefied or unconscious from alcohol or drugs; pass out. 2. to become exhausted or fall asleep from fatigue. v.t. 3. to stupefy, sedate, or intoxicate. 4. to strike suddenly; knock out. (often fol. by out)(often fol. by out)[1945?50; of expressive orig.; -onk perhaps copies conk2]Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.