Word family noun ability ≠ inability disability adjective able ≠ unable disabled verb enable ≠ disable adverb ably
From Longman Dictionary of Contemporary Englishunableun‧a‧ble /ʌnˈeɪbəl/ ●●● W2 adjective [not before noun] CAN'Tnot able to do something → inabilityunable to do something Lucy was unable to find out what had happened. Unable to sleep, I got up and made myself a drink.RegisterIn everyday English, people usually say that they can't/couldn't do something rather than are/were unable to do something:She couldn't find out what had happened.Examples from the Corpus
unable• Older people were much more likely than the young to be unable to describe what they meant by health.• If they don't, one should dismiss the idea of cars unable to get out of the garage as sensational rubbish-mongering.• When the police proved unable to handle them, the militia was called out.• When spot market prices rose, the utilities were unable to increase their rates.• But they were unable to produce perfect castings.• Tommy, unable to read, is none the wiser.• Security of tenure also means that a landlord may be unable to regain his house, if he wishes to.• What happens when a young husband and father is suddenly unable to work because of cancer?unable to do something• They were unable to find any link when other variables like prices and incomes were taken into account.• Ben was unable to get out of bed for four days.• Prevention education has been unable to halt this behavior, or even to make much of a dent in it.• The result has been that customers are often unable to log on to the system.• He seemed unable to meet the coroner's eyes, not daring even to look in his direction.• Tebbit found himself unable to outlaw the closed shop entirely.• Three kids trapped by them and unable to return home.• Of much of this process Coffin was a spectator; he was unable to tear himself away.• Well over eighty years of age, and unable to walk without support, he now rarely leaves his room. 