Dictionary.com
Thesaurus.com
Synonyms

keel over

British  

verb

  1. to turn upside down; capsize

  2. informal (intr) to collapse suddenly

"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
keel over Idioms  

  1. Collapse, as if in a faint; also, faint. For example, When she heard the awful news, she keeled over. This term alludes to a vessel rolling on its keel and capsizing. [Mid-1800s]

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

It’s the humidity, which has spiked to over 80%, that has them feeling ready to keel over between sets.

From The Wall Street Journal • Oct. 10, 2025

“I feel fine; I’ll probably keel over after I hang up the phone,” he joked.

From Los Angeles Times • Jul. 10, 2025

“I thought maybe I would keel over on the bench because I love it, I love it, I love it.”

From Seattle Times • Apr. 10, 2024

Some did not land on the target surface with perfect finesse: they might swing under or keel over the platform, for example.

From Scientific American • Aug. 5, 2021

They’re always afraid you’re about to keel over.

From "Water for Elephants" by Sara Gruen

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.