How to Say "deadly" in Spanish
The most common Spanish word for “deadly” is “mortal” — use 'mortal' when referring to something that is capable of causing death, often implying a natural or inherent danger..
mortal
/mor-TAL//moɾˈtal/
Examples
La mordedura de esta serpiente es mortal.
The bite of this snake is deadly.
La cobra tiene un veneno mortal.
The cobra has a deadly venom.
Para algunos, la envidia es un pecado mortal.
For some, envy is a mortal sin.
Adjective Placement
Like many Spanish adjectives, 'mortal' usually goes after the noun it describes (e.g., 'veneno mortal').
letal
/leh-TAHL//leˈtal/
Examples
El gas nervioso es un arma letal.
The nerve gas is a deadly weapon.
El veneno de esta araña es letal para los humanos.
The venom of this spider is lethal to humans.
Fue un error letal para su carrera política.
It was a fatal mistake for his political career.
La policía confiscó un arma letal en la escena.
The police confiscated a deadly weapon at the scene.
One size fits all
In Spanish, most adjectives that end in the letter 'l' don't change for gender. You can use 'letal' for both masculine and feminine things (e.g., 'un veneno letal' and 'una dosis letal').
Avoid adding -a or -o
Mistake: “Using 'letalo' or 'letala'.”
Correction: Always use 'letal'. To make it plural for more than one thing, just add '-es' to get 'letales'.
fatal
fah-TAHL/faˈtal/
Examples
El conductor sufrió heridas fatales en el accidente.
The driver suffered deadly injuries in the accident.
El accidente de coche fue fatal para los dos conductores.
The car accident was fatal for both drivers.
Ese fue un encuentro fatal que cambió el curso de la historia.
That was a fateful encounter that changed the course of history.
mortales
/mor-TAH-lehs//moɾˈtales/
Examples
El soldado recibió tres heridas mortales.
The soldier received three deadly wounds.
El guerrero sufrió varias heridas mortales.
The warrior suffered several deadly wounds.
Todos somos mortales y debemos aceptar el fin.
We are all mortal and must accept the end.
Making 'L' Words Plural
For words ending in 'l' like 'mortal', you make them plural by adding 'es' at the end.
Gender Consistency
Mistake: “Using 'mortalas' for feminine groups.”
Correction: The word 'mortales' stays the same for both masculine and feminine groups. Use 'los hombres mortales' and 'las mujeres mortales'.
asesino
/a-se-SI-no//aseˈsino/
Examples
Ese cuchillo de cocina es un peligro asesino.
That kitchen knife is a deadly danger.
El boxeador tiene un instinto asesino en el ring.
The boxer has a killer instinct in the ring.
Me lanzó una mirada asesina cuando derramé el café.
She shot me a murderous look when I spilled the coffee.
El gas tiene un efecto asesino si se inhala.
The gas has a deadly effect if inhaled.
Matching the Noun
When used to describe something, 'asesino' must match the gender and number of that thing. For example: 'un instinto asesino' (a killer instinct) but 'una mirada asesina' (a murderous look), because 'mirada' is feminine.
Mortal vs. Fatal
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