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nod off

British  

verb

  1. informal (intr, adverb) to fall asleep

"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
nod off Idioms  

  1. Fall asleep momentarily, doze, as in Grandma spends a lot of time in her rocking chair, nodding off now and then. This expression alludes to the quick involuntary dropping of one's head from an upright position when drowsy or napping. The verb nod alone was so used from the mid-1500s. Also see drop off, def. 1.

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.