loco: meaning, definition, pronunciation and examples
C1Informal, slang. The 'crazy' meaning is strongly colloquial and not used in formal writing.
Quick answer
What does “loco” mean?
Insane, crazy, or mentally deranged.
Audio
Pronunciation
Definition
Meaning and Definition
Insane, crazy, or mentally deranged.
Informally describes someone or something as wildly irrational, foolish, or out of control; can also be used playfully. In technical contexts, can refer to a locomotive.
Dialectal Variation
British vs American Usage
Differences
As slang for 'crazy', it is more common and somewhat more established in American English, influenced by Spanish. In British English, it's understood but less frequent and may feel like an Americanism. The technical 'locomotive' sense is used in both varieties.
Connotations
In both varieties, the slang sense is informal and often lighthearted. In American English, it can sometimes carry a slight 'wild west' or historical flavor.
Frequency
Slang usage is low-to-medium frequency in AmE, low frequency in BrE. Technical usage is rare for the general public but standard in rail contexts.
Grammar
How to Use “loco” in a Sentence
[Subject] is/goes loco.[Subject] drives [Object] loco.a loco [Noun] (e.g., a loco idea)Vocabulary
Collocations
Examples
Examples of “loco” in a Sentence
verb
British English
- Not used as a verb in standard BrE.
American English
- (Rare, non-standard) He was locoed by the intense heat. (meaning: driven crazy)
adverb
British English
- Not used as an adverb.
American English
- (Non-standard) He was acting loco. (Here 'loco' remains an adjective complement)
adjective
British English
- After the fifth call centre ringtone, I'm going completely loco.
- The entire plan sounds a bit loco, to be honest.
American English
- The constant construction noise is driving me loco.
- That's a loco idea, but it might just work.
Usage
Meaning in Context
Business
Virtually never used. Highly inappropriate.
Academic
Not used except in historical/cultural studies discussing slang or rail transport.
Everyday
Used informally among friends for humorous emphasis. 'This traffic is driving me loco!'
Technical
Used as an abbreviation for 'locomotive' in rail engineering and operations (e.g., 'diesel loco').
Watch out
Common Mistakes When Using “loco”
- Using it in formal writing or speech.
- Misspelling as 'louco' (Portuguese) or 'loko'.
- Using it as a standard adjective before a noun ('a loco person') which can sound unnatural; predicative use ('he is loco') is more common.
FAQ
Frequently Asked Questions
Not inherently rude, but it is very informal slang. It could be offensive if used to describe someone with a genuine mental health condition.
It derives from Spanish 'loco' meaning 'insane'. It entered American English in the 19th century, likely through contact in the Southwestern United States.
Yes, but primarily in the technical sense as a short form of 'locomotive' (e.g., 'The old steam loco is in the museum'). The slang 'crazy' sense is almost exclusively adjectival.
'Loco' is the most informal and stylistically marked (often with a humorous or American flavour). 'Crazy' is general informal. 'Mad' is common in BrE but can be more formal in compounds (e.g., 'madman'). 'Loco' is less versatile and rarely used figuratively for 'enthusiastic' ('crazy about football').
Insane, crazy, or mentally deranged.
Loco is usually informal, slang. the 'crazy' meaning is strongly colloquial and not used in formal writing. in register.
Loco: in British English it is pronounced /ˈləʊ.kəʊ/, and in American English it is pronounced /ˈloʊ.koʊ/. Tap the audio buttons above to hear it.
Phrases
Idioms & Phrases
- “drive someone loco”
- “go loco”
Learning
Memory Aids
Mnemonic
Imagine a LOCOmotive engine wildly careening off the tracks—completely **crazy** or **loco**.
Conceptual Metaphor
INSANITY IS LOSS OF CONTROL / A MACHINE MALFUNCTIONING (like a runaway train).
Practice
Quiz
In which context would the word 'loco' be MOST appropriate?