Many French and English adjectives ending in -able are spelt the same way and have the same meaning. Probable means “probable”, capable means “capable”, and durable means “durable”.

Both languages inherited this ending from Latin -abilis. In most cases, the English word came from French. The differences between French and English are usually quite small: French may have an accent that English lacks, Australian English may use “-our” where French uses “-or”, or the two languages may use different prefixes.

Words spelt the same in both languages

• Acceptable – “acceptable”
• Adaptable – “adaptable”
• Admirable – “admirable”
• Adorable – “adorable”
• Applicable – “applicable”
• Capable – “capable”
• Comparable – “comparable”
• Culpable – “culpable”
• Curable – “curable”
• Durable – “durable”
• Excusable – “excusable”
• Impracticable – “impracticable”
• Improbable – “improbable”
• Inapplicable – “inapplicable”
• Incomparable – “incomparable”
• Incurable – “incurable”
• Inexcusable – “inexcusable”
• Invariable – “invariable”
• Notable – “notable”
• Passable – “passable”
• Payable – “payable”
• Portable – “portable”
• Practicable – “practicable”
• Probable – “probable”
• Profitable – “profitable”
• Respectable – “respectable”
• Sociable – “sociable”
• Stable – “stable”
• Variable – “variable”
• Viable – “viable”

Words with small spelling differences

• Agréable – “agreeable”
• Confortable – “comfortable”
• Considérable – “considerable”
• Délectable – “delectable”
• Déplorable – “deplorable”
• Désirable – “desirable”
• Détestable – “detestable”
• Favorable – “favourable”
• Honorable – “honourable”
• Inacceptable – “unacceptable”
• Inévitable – “inevitable”
• Instable – “unstable”
• Mémorable – “memorable”
• Misérable – “miserable”
• Préférable – “preferable”
• Présentable – “presentable”
• Raisonnable – “reasonable”
• Redoutable – “redoubtable”
• Remarquable – “remarkable”
• Tolérable – “tolerable”
• Véritable – “veritable”
• Vulnérable – “vulnerable”

Most of these differences fall into one of three patterns. A French accent appears where English has none, as in considérable and “considerable”. Australian spelling keeps the “-our” ending in words such as “favourable” and “honourable”, while French keeps the shorter “-or”, as in favorable and honorable. A different prefix appears in a small number of pairs, as with inacceptable and “unacceptable”, or instable and “unstable”.

False friends and exceptions

• Formidable usually means “wonderful” or “terrific” in everyday French, closer to a strong compliment than a warning. English “formidable” describes something that inspires respect or unease because of its size, strength or difficulty, which is closer to the older sense the French word once carried.
• Disponible corresponds to “available” in meaning, but ends in -ible rather than -able.

Summary

French and English adjectives ending in -able are usually spelt the same way and carry the same meaning, since both languages inherited the ending from the Latin -abilis by a similar route. Where they differ, it is generally down to a French accent, an Australian “-our” spelling, or a different prefix, as with inacceptable and “unacceptable”. A small number of words, above all formidable, look alike but carry a different weight in each language.