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

See Examples For:

unable

My plan for them is to put the money in a trust to be managed by their uncle, with the option to be managed professionally if he feels unable to take on the role.

From MarketWatch ● Aug. 21, 2026

The Chargers were unable to cross the goal line from there, however, and walked off the field with a field goal.

From Los Angeles Times ● Aug. 21, 2026

Alcaraz has been replaced as world number two by Alexander Zverev after being unable to defend his Cincinnati Open title.

From BBC ● Aug. 20, 2026

European stock indexes were mixed, with gains in autos and semiconductors unable to lift the lift the Europe-wide Stoxx 600 index.

From The Wall Street Journal ● Aug. 20, 2026

Kennedy stood up, unable to hide his irritation.

From "Fallout: Spies, Superbombs, and the Ultimate Cold War Showdown" by Steve Sheinkin

Related Words

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