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
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
They did not literally escape, because they were still in his house and vulnerable to Olaf’s evil in loco parentis ways.
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
Should you eat the papas bravas the same night as the chicharrones locos, you may wish they did not both depend on the pineapple hot sauce and the cashew cream.
From New York Times ● Jul. 28, 2015
It doesn't matter if you're a goofy-foot or a regular-foot, if you've recently been married, are a loner, or are a family man-you're insane in the membrane, and olas locos is what you're after.
From Time Magazine Archive
The roll was called: seven "good and true" locos answered the call.
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
"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
“He acts like he was locoed to me,” declared Felix Burns, the horse wrangler, who, much to his disgust, had to “act in them fool pitchers” as well as handle the stock for the outfit.
From Ruth Fielding In the Saddle College Girls in the Land of Gold by Alice B. Emerson
Yuh've made many things plain to me that I was too locoed to see before.
From The Song of the Wolf by Frank Mayer
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
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