-ous becomes -eux
Many English adjectives ending in -ous have close French matches ending in -eux. This is one of the most useful word patterns in French. It can help with reading and guessing meaning, because a large number of English and French words come from the same Latin roots.
Examples such as dangerous → dangereux and curious → curieux show the pattern well.
This pattern is often reliable, but it is not a rule that always works. Some words follow other paths, and some have shifted in meaning over time.
The basic pattern
The usual pattern is:
- English -ous → French -eux
- English -ous → French -euse for feminine forms
Examples:
- dangerous → dangereux
- curious → curieux
- nervous → nerveux
- generous → généreux
- mysterious → mystérieux
- serious → sérieux
- ambitious → ambitieux
- courageous → courageux
Examples with feminine forms:
- dangerous → dangereuse
- curious → curieuse
- generous → généreuse
Examples:
- Un homme dangereux. “A dangerous man.”
- Une femme dangereuse. “A dangerous woman.”
- Un enfant curieux. “A curious child.”
- Une fille curieuse. “A curious girl.”
Common examples
Dangerous → dangereux
Examples:
- Ce chien semble dangereux. “That dog seems dangerous.”
- Cette route est dangereuse. “This road is dangerous.”
Related words:
- danger “danger”
- mettre en danger “to put at risk”
Curious → curieux
Examples:
- Il est très curieux. “He is very curious.”
- Je trouve cela curieux. “I find that strange.”
French curieux can also mean strange or odd.
Examples:
- C’est une curieuse histoire. “That is a strange story.”
Related words:
- curiosité “curiosity”
Nervous → nerveux
Examples:
- Il devient nerveux avant les examens. “He becomes nervous before exams.”
- Elle paraît nerveuse aujourd’hui. “She seems nervous today.”
Related words:
- les nerfs “nerves”
Generous → généreux
Examples:
- Il est très généreux avec ses amis. “He is very generous with his friends.”
- Elle a fait un geste généreux. “She made a generous gesture.”
Related words:
- générosité “generosity”
Mysterious → mystérieux
Examples:
- Il y a un bruit mystérieux dans la maison. “There is a mysterious sound in the house.”
- Elle a un sourire mystérieux. “She has a mysterious smile.”
Related words:
- mystère “mystery”
Cases where spelling changes more
Some words follow the pattern, but other parts of the word change as well.
Examples:
- ambitious → ambitieux
- cautious → prudent
- furious → furieux
- precious → précieux
- religious → religieux
The ending may still fit the pattern, but the whole word may not line up exactly.
Examples:
- Il est très ambitieux. “He is very ambitious.”
- Cette bague est précieuse. “This ring is precious.”
- Il est furieux contre son voisin. “He is furious with his neighbour.”
Related words:
- ambition “ambition”
- furie “fury”
- prix “price”
Cases where the pattern fails
Not every English -ous word becomes French -eux.
Examples:
- famous → célèbre
- jealous → jaloux
- enormous → énorme
- poisonous → toxique
- glamorous → glamour
Examples:
- Il est célèbre dans son pays. “He is famous in his country.”
- Elle est jalouse de sa sœur. “She is jealous of her sister.”
- Cet animal est toxique. “This animal is poisonous.”
You cannot safely change every English -ous word into -eux.
Watch out for false friends
Some words look closely linked but have grown apart.
Curious → curieux
As already seen, curieux can mean more than curious.
Examples:
- Je trouve cela curieux. “I find that strange.”
- Un curieux personnage est arrivé. “A strange person arrived.”
English curious usually stays closer to the idea of wanting to know things.
Serious → sérieux
French sérieux can mean serious, but also reliable or solid.
Examples:
- Cette entreprise semble sérieuse. “This company seems reliable.”
- Il faut être sérieux. “You must be serious.”
Larger word families
Many of these words belong to larger groups.
| English noun | English adjective | French noun | French adjective |
|---|---|---|---|
| danger | dangerous | danger | dangereux |
| mystery | mysterious | mystère | mystérieux |
| courage | courageous | courage | courageux |
| nerve | nervous | nerf | nerveux |
| generosity | generous | générosité | généreux |
Learning families often helps more than learning single words.
Useful examples in full sentences
- Le brouillard rend la route dangereuse. “The fog makes the road dangerous.”
- Mon fils est très curieux de nature. “My son is naturally very curious.”
- Elle devient nerveuse avant une réunion. “She becomes nervous before a meeting.”
- Cet homme est très généreux avec son temps. “That man is very generous with his time.”
- Il y a quelque chose de mystérieux dans cette maison. “There is something mysterious about this house.”
- Son frère est ambitieux depuis son enfance. “His brother has been ambitious since childhood.”
Related patterns
The English -ous → French -eux pattern belongs to a wider set of useful links.
Examples:
- English -ty → French -té
- English -ncy → French -nce
- English -ity → French -ité
Examples:
- liberty → liberté
- frequency → fréquence
- activity → activité
These links help with guessing meaning, but they should be treated as guides rather than fixed rules.
Summary
- English adjectives ending in -ous often match French adjectives ending in -eux.
- Feminine forms usually end in -euse.
- Many pairs come from shared Latin roots.
- Common examples include dangerous → dangereux and curious → curieux.
- Some words fail to follow the pattern, such as famous → célèbre.
- Learning whole word families often works better than learning isolated words.
