As with adjectives ending in -ible, many French and English adjectives ending in -able are spelt the same way and carry the same meaning. Probable is “probable”, capable is “capable”, and durable is “durable”. Both languages took this ending from the Latin -abilis, added to a verb to describe something that can be done to it or by it, and English received most of these words by way of French. Where the two languages part company, it is usually for one of three reasons: a French accent that English does not carry, an Australian spelling with “-our” where French keeps “-or”, or a different prefix at the front of the word.

Below are the main groups of examples.

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.