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
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
He was also asked about his understanding of the term "in loco parentis", namely having responsibilities for children in the absence of their parents or guardians.
From BBC ● Jan. 24, 2024
“She can get married if she has the permission of her legal guardian, acting in loco parentis,” Klaus said.
From "The Bad Beginning" by Lemony Snicket
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
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
People around here, they call this place the casa de locos, but they don't understand.
From Time Magazine Archive
Of course we stop to have a look at the engine, one of those splendid Reading locos with the three great driving wheels.
From Plum Pudding Of Divers Ingredients, Discreetly Blended & Seasoned by Christopher Morley
Moreover, he is locoed and has other defects.
From Time Magazine Archive
Ev’ry time she got where the trail runs ’longside the wagon-road, none of them locoed bull’s-eye Simpson 253 vehicles was a-passin’.
From Alec Lloyd, Cowpuncher by Eleanor Gates
I’ve got a little shack down on the Rabbit-Ear—which is a crick, for all the name some locoed ignoramus give it.
From The Ranchman by Charles Alden Seltzer
Yes, men, he certainly is bumped in the bean and locoed in his arms.
From The Snow-Burner by Henry Oyen
Oh, yes," agreed the girl, "there's not a doubt but that she's plumb locoed!
From Hope Hathaway A Story of Western Ranch Life by Frances Parker
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Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
