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:
This is a place that has driven the Three Lions absolutely loco.
From The Wall Street Journal ● Jul. 5, 2026
"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
On the return journey, a bolt sheared on what is now more widely known as the Penydarren loco, causing the boiler to leak.
From BBC ● Feb. 24, 2024
“El viejo loco rambles on. I am tired, Esperanza. You are right. But I’ll rest soon. It’s been a good life. Raise him well, nieta.”
From "The Mark of Athena" by Rick Riordan
Someone who prefers potatoes is getting way less for their money than someone who’s locos for Doritos.
From The Verge ● Jan. 6, 2022
Recommended Dishes Vegan chicharrones locos; papas bravas; shaved cauliflower; green mole with burrata; sardine tostada; octopus salad.
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
As if the country were ever quiet, crowded as it was with locos and dogs and sabots.
From Balloons by Bibesco, Elizabeth
Moreover, he is locoed and has other defects.
From Time Magazine Archive
I was too badly "locoed" to tell a good horse from a bad one; in fact I wasn't fit for anything, unless it would have been a Mail carrier between "Denning's Bridge" and Matagorda.
From A Texas Cow Boy or, fifteen years on the hurricane deck of a Spanish pony, taken from real life by Siringo, Chas. A.
Once more, I guess, I was locoed for the minute.
From The Real Man by Lynde, Francis
If locoed animals can be turned into a field of alfalfa, a large proportion of them will recover with no further treatment.
From Special Report on Diseases of Cattle by United States. Bureau of Animal Industry
He’s a pretty bird, but if he’s locoed, he’d better be dead than afoot—poor creature.”
From Ruth Fielding In the Saddle College Girls in the Land of Gold by Emerson, Alice B.
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.
