unable

American  

[uhn-ey-buhl] / ʌnˈeɪ bəl /

adjective

1. lacking the necessary power, competence, etc., to accomplish some specified act.

   He was unable to swim.

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unable British  

/ ʌnˈeɪbəl /

adjective

1. lacking the necessary power, ability, or authority (to do something); not able

2. archaic incompetent

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Synonym Usage

See incapable.

Etymology

Origin of unable

First recorded in 1350–1400; Middle English; un- ¹ + able

Explanation

If you're unable to do something, you just can't do it. This isn't necessarily a bad thing! You may be unable to tell a lie, no matter how much you want to blame your brother for breaking that window. When we're unable, we're incapable. If you're unable to speak French, but you speak German fluently, you might choose to spend the summer in Berlin rather than Quebec City. And when your neighbor is unable to walk her dog during the day, you could volunteer to walk it after school. Being unable is either "lacking ability," or "lacking power."

Example Sentences

Unable to move properly because of injuries to her leg, she tried unsuccessfully to force the doors open.

From BBC • May 20, 2026

Unable to depend on natural snowfall, about 80 percent of ski areas in the Southeast and Midwest, nearly 50 percent in the Northeast, and 10 percent in the West now rely on snowmaking.

From Slate • Apr. 11, 2026

Unable to run tours into North Korea, he has been offering trips through border areas so customers can catch glimpses into the secretive state from a distance.

From Barron's • Mar. 29, 2026

Unable to participate in this year’s WBC as he recovers from offseason left elbow surgery, Hernández left Dodgers camp to spend the first leg of the tournament with Team Puerto Rico.

From Los Angeles Times • Mar. 14, 2026

Unable to make a sound, I slapped Dad’s arm.

From "The Line Tender" by Kate Allen

Related Words

• helpless
• impotent
• inadequate
• incapable
• not able
• powerless
• sidelined
• unfit
• weak