English uses unusual and unusually to express deviation from the normal or expected. French offers several adjectives and adverbs that convey this idea with varying degrees of intensity, from slightly unexpected to strikingly out of the ordinary. The choice depends on whether the English word describes something strange, rare, exceptional, surprising, or simply not typical.

Unusual

The most common French equivalents of unusual are inhabituel, peu habituel, inhabituel pour, bizarre, étrange, curieux, peu commun, rare, exceptionnel, and hors du commun. Selection depends on context.

Inhabituel, peu habituel

Inhabituel is the standard word for “not habitual” or “not typical.” Peu habituel softens the idea and is useful when the situation is only mildly unexpected.

Examples:

• C’est inhabituel.
  “It’s unusual.”
• Sa réaction est peu habituelle.
  “His reaction is unusual.”
• Il est inhabituel pour elle d’être en retard.
  “It’s unusual for her to be late.”
• Un froid aussi tôt en automne est peu habituel.
  “Such cold so early in autumn is unusual.”

Peu commun, rare

These express rarity rather than oddness.

Examples:

• C’est peu commun dans la région.
  “It’s unusual in the region.”
• Ce type de plante est rare ici.
  “This type of plant is unusual here.”

Hors du commun, exceptionnel

Useful for something markedly outside ordinary limits.

Examples:

• Un talent hors du commun.
  “An unusual level of talent.”
• Un succès exceptionnel pour un débutant.
  “An unusual success for a beginner.”

Bizarre, étrange, curieux

These emphasise strangeness or oddity rather than rarity.

Examples:

• C’est étrange qu’il n’ait pas appelé.
  “It’s unusual that he didn’t call.” (Implying it seems odd.)
• Une situation assez bizarre.
  “A rather unusual situation.”
• C’est curieux qu’elle ait refusé.
  “It’s unusual that she refused.” (Carries a sense of “that’s odd.”)

Pas comme d’habitude

A natural everyday phrasing for “not like usual.”

Examples:

• Aujourd’hui, il n’est pas comme d’habitude.
  “Today he’s acting unusually.”
• Le service était pas comme d’habitude.
  “The service was unusual.” (Meaning “not as it normally is.”)

Unusually

English unusually often modifies adjectives or verbs, signalling an unexpected degree of something. French does not use a direct adverb equivalent but instead draws on adverbs and constructions that express exception, intensity, or departure from the ordinary.

Common equivalents include inhabituellement, exceptionnellement, étrangement, curieusement, particulièrement, singulièrement, and de façon inhabituelle.

Inhabituellement

Directly parallels “unusually,” though used less frequently than in English. Works well in careful or written French.

Examples:

• Il faisait inhabituellement chaud.
  “It was unusually hot.”
• Elle était inhabituellement silencieuse.
  “She was unusually quiet.”

Exceptionnellement

Expresses an exceptional degree.

Examples:

• Le train est exceptionnellement complet.
  “The train is unusually full.”
• Il était exceptionnellement patient.
  “He was unusually patient.”

Étrangement, curieusement

Used when “unusually” carries an element of oddness.

Examples:

• Elle était étrangement calme.
  “She was unusually calm.”
• Il a réagi curieusement.
  “He reacted unusually.” (Meaning strangely.)

Particulièrement, singulièrement

Often used instead of “unusually” when the English largely means “very” or “especially.”

Examples:

• Un repas particulièrement simple.
  “An unusually simple meal.”
• Un ciel singulièrement sombre.
  “An unusually dark sky.”

De manière inhabituelle, de façon inhabituelle

Neutral phrases that work when the action itself is performed in an unusual way.

Examples:

• Il s’est comporté de manière inhabituelle.
  “He behaved unusually.”
• Le moteur tourne de façon inhabituelle.
  “The engine is running unusually.”

Summary

• Unusual can correspond to inhabituel, peu habituel, peu commun, rare, bizarre, étrange, curieux, hors du commun, or exceptionnel, depending on whether the context implies rarity, oddness, or exception.
• Unusually often maps to inhabituellement, exceptionnellement, étrangement, curieusement, particulièrement, singulièrement, or structures like de manière inhabituelle.
• Everyday French often expresses “unusually” through other constructions rather than a single direct adverb.