Many English nouns ending in -ncy (usually -ancy or –ency) have close French matches ending in -nce. This is a useful pattern and can help with reading and building French words. In many cases, English -ncy and French -nce come from the same Latin root. English often added -y at the end over time, while French usually kept -e.

This pattern is real and often works, but it is not a rule that always works. It is best treated as a strong guide rather than a machine-like conversion method.

The basic pattern

The usual pattern is:

• English -ncy → French -nce

Examples:

• frequency → fréquence
• dependency → dépendance
• urgency → urgence
• consistency → consistance
• tendency → tendance
• efficiency → efficience
• deficiency → déficience
• expectancy → espérance
• hesitancy → hésitance

Many of these nouns describe:

• a state
• a quality
• a condition
• a repeated tendency
• a degree of something

Common examples

Frequency → fréquence

Frequency and fréquence have almost the same meaning.

Examples:

• La fréquence des accidents augmente. “The frequency of accidents is rising.”
• Nous avons augmenté la fréquence des contrôles. “We increased the frequency of checks.”

Related words:

• fréquent “frequent”
• fréquemment “frequently”

Dependency → dépendance

Dependency often becomes dépendance.

Examples:

• La dépendance au sucre peut être forte. “Dependence on sugar can be strong.”
• Il existe une dépendance économique entre les deux pays. “There is economic dependence between the two countries.”

Related words:

• dépendre de “to depend on”
• indépendance “independence”

Urgency → urgence

Examples:

• Il y a une urgence médicale. “There is a medical emergency.”
• L’urgence de la situation est évidente. “The urgency of the situation is obvious.”

Related words:

• urgent “urgent”

Tendency → tendance

Examples:

• Il a une tendance à exagérer. “He has a tendency to exaggerate.”
• Les tendances changent vite. “Trends change quickly.”

Related words:

• avoir tendance à “to tend to”
• penchant “leaning”
• mode “fashion or trend”

Deficiency → déficience

Examples:

• La déficience visuelle touche beaucoup de personnes. “Visual impairment affects many people.”
• Une déficience du système a été trouvée. “A system weakness was found.”

Related words:

• déficit “deficit”
• manque “lack”

Cases where meanings drift apart

Some words look like direct twins but have grown apart in meaning.

Consistency → consistance

This one needs care.

English consistency often means:

• steadiness
• not changing
• logical agreement

French consistance often means:

• thickness
• texture
• substance

Examples:

• La soupe a une bonne consistance. “The soup has a good texture.”
• Cette crème a une consistance légère. “This cream has a light texture.”

For English consistency in the sense of steadiness, French often uses other words.

Examples:

• La cohérence de son travail est remarquable. “The consistency of his work is remarkable.”
• La régularité est importante. “Consistency is important.”

Related words:

• cohérence “coherence”
• régularité “regularity”

Cases where French uses another ending

The pattern does not always work.

English -ncy words sometimes match French words with a different ending.

Examples:

• vacancy → vacance in some uses, but often poste vacant or another wording depending on meaning
• fluency → aisance
• pregnancy → grossesse

Examples:

• Elle parle avec aisance. “She speaks fluently.”
• Sa grossesse avance bien. “Her pregnancy is progressing well.”

You cannot safely build every French word by replacing -ncy with -nce.

Cases where English has -ence as well

English sometimes already has two forms.

Examples:

• dependence and dependency
• insistence and insistency
• competence and competency

French may use one word where English has two.

Examples:

• dependence and dependency → dépendance
• competence and competency → compétence

Examples:

• Sa compétence est reconnue. “His skill is recognised.”
• Cette compétence est utile au travail. “This skill is useful at work.”

Larger groups built from the same roots

Many of these words belong to families.

Examples:

English adjective	English noun	French adjective	French noun
frequent	frequency	fréquent	fréquence
dependent	dependency	dépendant	dépendance
urgent	urgency	urgent	urgence
deficient	deficiency	déficient	déficience
hesitant	hesitancy	hésitant	hésitance

Learning the family often helps more than learning one word by itself.

Useful examples in full sentences

• La fréquence des trains est plus élevée aujourd’hui. “The frequency of trains is higher today.”
• Sa dépendance aux jeux vidéo lui pose des problèmes. “His dependence on video games causes him problems.”
• L’urgence de la demande nous oblige à agir vite. “The urgency of the request forces us to act quickly.”
• Cette tendance devient plus forte chaque année. “This tendency becomes stronger each year.”
• Une déficience technique a interrompu le système. “A technical fault interrupted the system.”
• Son hésitance était visible. “His hesitation was visible.”

Related patterns

The -ncy → -nce pattern belongs to a wider group of English and French links.

Other common pairs include:

• English -ty → French -té
• English -ity → French -ité
• English -ous → French -eux or -euxse in some cases
• English -al → French -al or -el

Examples:

• liberty → liberté
• activity → activité
• curiosity → curiosité

These patterns can help you guess words, but they are guides rather than rules.

Summary

• English words ending in -ncy often match French words ending in -nce.
• The pattern comes largely from shared Latin roots.
• Many common pairs work directly, such as frequency → fréquence and dependency → dépendance.
• Some words drift apart in meaning, such as consistency → consistance.
• Some English -ncy words use a different French form altogether, such as pregnancy → grossesse.
• Word families are often easier to learn than single words in isolation.