English has many verbs that end in “fy,” like certify, simplify, and justify, and they almost all come from French. The French versions end in “fier” instead, so certify becomes certifier, simplify becomes simplifier, and justify becomes justifier. The pattern is simple for most of them: you just change the ending “fy” to “fier.” These are all regular verbs in French, and they follow the same conjugation pattern as other verbs ending in “er.” Here are the most common ones with an example of each.

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Verbs that follow the rule

For these verbs, you change the ending “fy” to “fier.”

Amplify becomes amplifier

Nous devons amplifier le son.
“We must amplify the sound.”

Certify becomes certifier

Je certifie que ce document est vrai.
“I certify that this document is true.”

Clarify becomes clarifier

Tu dois clarifier ta position.
“You must clarify your position.”

Classify becomes classifier

Ils classifient les plantes par espèce.
“They classify plants by species.”

Codify becomes codifier

Le gouvernement veut codifier ces règles.
“The government wants to codify these rules.”

Deify becomes déifier

Les fans déifient cette chanteuse.
“The fans deify this singer.”

Exemplify becomes exemplifier

Cet exemple exemplifie le problème.
“This example exemplifies the problem.”

Fortify becomes fortifier

On boit cette vitamine pour fortifier le corps.
“We drink this vitamin to fortify the body.”

Glorify becomes glorifier

Il ne faut pas glorifier la violence.
“You must not glorify violence.”

Gratify becomes gratifier

Le patron gratifie ses employés de primes.
“The boss gratifies his employees with bonuses.”

Horrify becomes horrifier

Ces images horrifient les spectateurs.
“These images horrify the viewers.”

Identify becomes identifier

Je n’arrive pas à identifier cet oiseau.
“I cannot identify this bird.”

Intensify becomes intensifier

La pluie va s’intensifier dans la soirée.
“The rain will intensify in the evening.”

Justify becomes justifier

Tu n’as pas à justifier tes choix.
“You do not have to justify your choices.”

Liquefy becomes liquéfier

La chaleur liquéfie le beurre.
“The heat liquefies the butter.”

Magnify becomes magnifier

Ce texte magnifie la beauté de la nature.
“This text magnifies the beauty of nature.”

Modify becomes modifier

Nous devons modifier nos plans.
“We must modify our plans.”

Mollify becomes mollifier

Il essaie de mollifier sa colère.
“He tries to mollify his anger.”

Mummify becomes momifier

Les Égyptiens momifiaient leurs morts.
“The Egyptians mummified their dead.”

Mystify becomes mystifier

Ce tour de magie mystifie le public.
“This magic trick mystifies the audience.”

Notify becomes notifier

La banque va notifier les clients par email.
“The bank will notify the clients by email.”

Objectify becomes objectifier

Il ne faut pas objectifier les personnes.
“You must not objectify people.”

Personify becomes personnifier

Il personnifie la gentillesse.
“He personifies kindness.”

Purify becomes purifier

Cette plante purifie l’air de la maison.
“This plant purifies the air in the house.”

Qualify becomes qualifier

L’équipe s’est qualifiée pour la finale.
“The team qualified for the final.”

Quantify becomes quantifier

On peut quantifier les résultats.
“We can quantify the results.”

Ratify becomes ratifier

Le président va ratifier le traité.
“The president will ratify the treaty.”

Rectify becomes rectifier

Je dois rectifier une erreur.
“I must rectify an error.”

Reify becomes réifier

Ce concept réifie une idée abstraite.
“This concept reifies an abstract idea.”

Simplify becomes simplifier

Il faut simplifier les instructions.
“You must simplify the instructions.”

Solidify becomes solidifier

Le froid solidifie l’eau.
“The cold solidifies the water.”

Specify becomes spécifier

Tu dois spécifier la quantité.
“You must specify the quantity.”

Stratify becomes stratifier

La société est fortement stratifiée.
“Society is strongly stratified.”

Terrify becomes terrifier

Ce film terrifie les enfants.
“This film terrifies the children.”

Testify becomes témoigner (not testifier, which is rare)

Il va témoigner au procès.
“He will testify at the trial.”

Unify becomes unifier

Charlemagne a unifié une grande partie de l’Europe.
“Charlemagne unified a large part of Europe.”

Verify becomes vérifier

Je vérifie les informations avant de publier.
“I verify the information before publishing.”

Vitrify becomes vitrifier

On utilise ce produit pour vitrifier le parquet.
“We use this product to vitrify the floor.”

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Summary

Most English verbs ending in “fy” become French verbs ending in “fier,” and the meaning stays the same. These are all regular “er” verbs, so they conjugate like parler or manger. Learning this simple rule helps you guess many French verbs from English without needing a dictionary.