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How to Say "insane" in Spanish

The most common Spanish word for “insane” is “loco” — use 'loco' for general expressions of craziness, driving someone crazy, or describing something wildly impractical or unbelievable. It's the most common and versatile term.

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loco

LOH-kohˈlo.ko

AdjectiveA2Informal to Neutral
Use 'loco' for general expressions of craziness, driving someone crazy, or describing something wildly impractical or unbelievable. It's the most common and versatile term.
A cartoon illustration of a person with wide, chaotic eyes and wildly disheveled hair, symbolizing a state of craziness.

Examples

Me parece una idea loca construir una casa en la cima de una montaña.

It seems like a crazy idea to me to build a house on a mountaintop.

El ruido constante me está volviendo loco.

The constant noise is driving me crazy.

Tuvo la loca idea de empezar un negocio sin dinero.

He had the crazy idea of starting a business with no money.

Después del accidente, todos pensaban que estaba loco.

After the accident, everyone thought he was insane.

Matching the Noun

Like most Spanish adjectives, 'loco' changes to match the person or thing it describes. Use 'loco' for masculine things ('el hombre loco'), 'loca' for feminine ('la idea loca'), 'locos' for plural masculine ('los perros locos'), and 'locas' for plural feminine ('las mujeres locas').

Ser vs. Estar: A Key Difference

Use 'ser loco' to say someone IS a crazy person (it's part of their identity). Use 'estar loco' to say someone IS BEING crazy (it's a temporary state or action). 'Es loco' is a judgment; 'Está loco' often describes a reaction.

Mixing up 'Ser' and 'Estar'

Mistake: “Mi hermano es loco porque compró un coche nuevo sin decírselo a su esposa.”

Correction: Mi hermano está loco... — You're talking about a specific crazy action (buying the car), not saying he is fundamentally an insane person. Use 'estar' for temporary states or behavior.

demente

deh-MEN-tehdeˈmente

AdjectiveB1Formal to Neutral
Choose 'demente' when referring to a more formal or clinical state of mental derangement, or when describing behavior that is seriously irrational and potentially harmful.
A storybook illustration of a person sitting on the floor, intently staring at a single sock held in their hands with a distressed expression, depicting an irrational or disturbed state of mind.

Examples

El comportamiento errático del sospechoso lo llevó a ser considerado demente.

The suspect's erratic behavior led to him being considered insane.

La idea de escalar esa montaña sin equipo me parece demente.

The idea of climbing that mountain without equipment seems insane to me.

Su comportamiento en la reunión fue completamente demente.

His behavior in the meeting was completely mad.

Tuvieron que detener a la mujer demente.

They had to stop the insane woman.

Gender Consistency

As an adjective, 'demente' is special because it always stays the same, whether you are describing a masculine or feminine noun: 'el plan demente' (the insane plan) and 'la propuesta demente' (the insane proposal).

psicótico

AdjectiveB2Formal (clinical) to Informal (colloquial)
Use 'psicótico' specifically when referring to a clinical mental health condition involving psychosis, or informally (and less accurately) to describe a sudden, extreme loss of control.

Examples

La falta de sueño le provocó un estado casi psicótico.

The lack of sleep caused him to enter an almost psychotic state.

Choosing between 'loco' and 'demente'

Learners often confuse 'loco' and 'demente'. Remember that 'loco' is much broader, used for everyday craziness and impractical ideas, while 'demente' is more serious and closer to clinical insanity or extreme irrationality.

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