unable

The word “unable” means not having the ability, power, or means to do something. In plain terms, lacking the power, skill, or opportunity to do something.

“Unable” is pronounced uhn-AYBL (/ʌnˈeɪbl̩/ in IPA).

Here is “unable” used in a sentence: “He was unable to attend the meeting because of a flight delay.”

The opposite of “unable” — its antonyms — is able.

“Unable” is an adjective.

The word “unable” comes from Middle English. From Middle English unable, formed from un- ("not") plus able.

“Unable” is a fairly common word in modern English, usually learned at around the B1 level.

Unable is an adjective describing a lack of ability — "I was unable to attend." Disable is a verb meaning to switch something off or take away a capability, as in "disable the alarm." The confusion comes from their shared root, but unable describes a state, while disable describes an action that causes one.

The direct opposite is "able," meaning you have the ability, power, or means to do something. Other positives include capable and competent. Where unable signals a limit or barrier, able signals that the path is open. Simply removing the "un-" prefix flips the meaning entirely.

The two overlap, but unable often points to a specific situation — "unable to make it today" — while incapable suggests a broader, more lasting lack of ability, as in "incapable of lying." Being unable to do one thing does not make you incapable in general; incapable is the stronger, more sweeping word.