- chloral hydrate or any similar rapidly acting drug, especially one put in a drink secretly to make the drinker unconscious.
Origin of knockout drops
First recorded in 1890–95
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
- slang a drug secretly put into someone's drink to cause stupefactionSee also Mickey Finn
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012