Most French adjectives are easy:
add -e for the feminine, add -s for the plural.
But of course, it’s French… so there are a few exceptions!
If you’re new to this topic, start with my article “French Adjectives Made Easy: Masculine, Feminine and Plural Forms”. It explains how regular adjectives work.
This lesson will take you a step further by exploring irregular adjectives: the ones that change in unexpected but fascinating ways.
Don’t worry.
Irregular adjectives often follow predictable patterns.
Once you know these patterns, they’re not so scary anymore!
1️⃣ -eux → -euse
Adjectives ending in -eux become -euse in the feminine form.
| Masculine | Feminine | English |
|---|---|---|
| heureux | heureuse | happy |
| curieux | curieuse | curious |
| sérieux | sérieuse | serious |
| nerveux | nerveuse | nervous |
| généreux | généreuse | generous |
🪄 Tip: Most adjectives with “-eux” change the ending to “-euse”.
It’s one of the most regular “irregular” patterns in French.
2️⃣ -eur → -euse
Adjectives ending in -eur often become -euse in the feminine form.
| Masculine | Feminine | English |
|---|---|---|
| travailleur | travailleuse | hardworking |
| menteur | menteuse | dishonest |
| rêveur | rêveuse | dreamy |
| flatteur | flatteuse | flattering |
| moqueur | moqueuse | mocking |
🪄 Tip: These adjectives often describe personality or behavior.
They look similar to the -eux → -euse pattern.
3️⃣ -if → -ive, -f → -ve
Adjectives ending in -if or -f change to -ive or -ve in the feminine.
| Masculine | Feminine | English |
|---|---|---|
| actif | active | active |
| sportif | sportive | sporty |
| naïf | naïve | naive |
| impulsif | impulsive | impulsive |
| créatif | créative | creative |
| neuf | neuve | new |
| vif | vive | lively |
| bref | brève | brief |
🪄 Tip: Both patterns make the ending softer in pronunciation — from “f” to “v”.
4️⃣ -er → -ère
These adjectives change the -er ending to -ère in the feminine.
| Masculine | Feminine | English |
|---|---|---|
| cher | chère | expensive, dear |
| léger | légère | light |
| fier | fière | proud |
| dernier | dernière | last |
| étranger | étrangère | foreign |
5️⃣ Double Consonant + e
Some adjectives double the final consonant before adding -e.
You’ll often see this with -el, -en, -on, or -et endings.
| Masculine | Feminine | English |
|---|---|---|
| bon | bonne | good |
| mignon | mignonne | cute |
| ancien | ancienne | old, former |
| cruel | cruelle | cruel |
| net | nette | clear, neat |
6️⃣ Completely Irregular Adjectives
Some adjectives change completely: you just have to memorize them.
Luckily, there aren’t too many!
| Masculine | Feminine | English |
|---|---|---|
| beau | belle | beautiful |
| nouveau | nouvelle | new |
| vieux | vieille | old |
| blanc | blanche | white |
| fou | folle | crazy |
| gentil | gentille | kind |
| doux | douce | soft, sweet |
| faux | fausse | false |
| favori | favorite | favorite |
| grec | grecque | Greek |
| gros | grosse | big, fat |
| long | longue | long |
| nul | nulle | bad, useless |
| roux | rousse | red-haired |
7️⃣ Extra Masculine Form (before vowels or silent H)
Some masculine adjectives have an extra masculine form used before words starting with a vowel or a silent “h”.
This makes pronunciation smoother.
| Masculine | Masculine (before vowel/H) | Feminine | English |
|---|---|---|---|
| beau | bel | belle | beautiful |
| nouveau | nouvel | nouvelle | new |
| vieux | vieil | vieille | old |
| fou | fol | folle | crazy |
🗣️ Examples:
- un bel homme → a handsome man
- un vieil ami → an old friend
- un nouvel appartement → a new apartment
- un fol espoir → a crazy hope
How to Remember Them
✅ Look for patterns: many “irregular” adjectives belong to a family (-if/-ive, -eux/-euse, etc.)
✅ Say both forms aloud when you learn a new adjective.
✅ Don’t learn isolated words, but pairs:
un homme actif → une femme active
un garçon curieux → une fille curieuse
Quiz
And now, let’s take this short quiz to see if everything is clear!
Final Thought
Irregular adjectives make your French sound more natural and expressive.
Once you know the patterns, you’ll start to recognize them everywhere and your speech will sound smoother and more confident!
Want to practice using these adjectives with a native French teacher?
Book your online lesson now and start speaking naturally in real conversation! 💬🇫🇷