adjective
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slang insane
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(of an animal) affected with loco disease
noun
verb
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to poison with locoweed
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slang to make insane
noun
adjective
Other Word Forms
Noun Inflected Forms
Etymology
Origin of loco
1835–45, < Spanish: insane
Explanation
If someone calls you loco, it means they think you're nutty or eccentric. Your friends will think your dog is completely loco if she spends hours every day chasing her own tail. You can use the slang term loco when you're commenting on the craziness or irrationality of a person or situation. You might say, for example: "This meeting is totally loco — everyone's talking at the same time!" Loco comes from American English, which borrowed it from the Spanish loco, "insane." Its roots are uncertain, but it may stem from the Arabic lauqa, "fool."
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.
See Examples For:
Coaches often serve in loco parentis, guiding a developing prospect not only through training and tournaments but also the awkward riddles of growing up.
From The Wall Street Journal ● Dec. 23, 2025
"The loco pilot, on observing the herd of elephants, applied emergency brakes. However, elephants dashed with the train," he said.
From Barron's ● Dec. 20, 2025
Starting with an ominous echoing sound, he begins to sing “Como Basquiat, ‘toy bien loco como Basquiat” over a simple trap beat.
From Los Angeles Times ● Oct. 1, 2024
Near Pike Place Market is Musubi Kai, doing Pacific Island rice bowls like poke and loco moco along with a dozen riffs on Spam musubi.
From Seattle Times ● May 4, 2024
And although admiring Joe Mondragon, they also thought he was a jerk—you had to be loco to ask for a kick in the ass like that.
From "The Milagro Beanfield War" by John Nichols
Someone who prefers potatoes is getting way less for their money than someone who’s locos for Doritos.
From The Verge ● Jan. 6, 2022
Just after I accepted the fact that I was in love with a dish called vegan chicharrones locos, a phrase from Freud ran through my head.
From New York Times ● Jul. 28, 2015
And it looks like vegan chicharrones locos at El Rey.
From New York Times ● Jul. 28, 2015
Some of the locos blow up a few feet and settle back on the tracks as if heaving a big sigh.
From Time Magazine Archive
"Beat, by thunder!" roared the locos, in grand chorus; and in the modern classics of the Bowery, "they wasn't any thing else."
From The Humors of Falconbridge A Collection of Humorous and Every Day Scenes by Falconbridge
Moreover, he is locoed and has other defects.
From Time Magazine Archive
We were all acquainted with the country from Running Water north, but had never been south of it; hence us having to depend on the "locoed" buffalo-hunter's directions.
From A Texas Cow Boy or, fifteen years on the hurricane deck of a Spanish pony, taken from real life by Chas. A. Siringo
An’ that locoed ol’ bum running ’round loose with it.
From The Snow-Burner by Henry Oyen
"Of all th' locoed layouts I ever run up against this here mesa top takes th' prize," he finished in disgust.
From Hopalong Cassidy by Clarence E. Mulford
"The old man is a bit locoed on this rebellion theory," mused Herbert as he went along.
From The Great Gold Rush A Tale of the Klondike by W. H. P. (William Henry Pope) Jarvis
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.
