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
It’s been bien loco, like I say in the song.
From Los Angeles Times ● Sep. 4, 2025
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
“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
And it looks like vegan chicharrones locos at El Rey.
From New York Times ● Jul. 28, 2015
Recommended Dishes Vegan chicharrones locos; papas bravas; shaved cauliflower; green mole with burrata; sardine tostada; octopus salad.
From New York Times ● Jul. 28, 2015
Thanks to the cold Humboldt Current, Chile has the world's most unusual seafood: erizos, giant sea urchins; picoroccos, beaked shell fish that taste like crab; and the giant abalones known as locos.
From Time Magazine Archive
Cicero expresses himself plainly on this subject: “Qui multa voluerit meminisse, multa sibi loca comparet: oportet multos comparare locos, ut in multis locis multas imagines collocemus.”
From Curiosities of Medical Experience by J. G. (John Gideon) Millingen
Moreover, he is locoed and has other defects.
From Time Magazine Archive
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
Reckon I must ’a’ been locoed, or, like ’nuff that ar ole hermutt’s done played a trick on me.
From Two Wyoming Girls and Their Homestead Claim A Story for Girls by Carrie L. Marshall
When people get locoed this way, the only thing is to humor them and give them a chance to rest satisfied in something––no matter what, much,––only so 187 they are not hectored.
From The Eye of Dread by Payne Erskine
“Better, I see,” I observed, “but heavens you were locoed this morning! talking about the resurrection, the quaking earth, and the dead rolling out from their graves!”
From Where Strongest Tide Winds Blew by Robert McReynolds
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