Unable means not able to do something. It describes a lack of power, skill, permission, or opportunity to act.
Formed by adding the negative prefix "un-" to "able," which comes from Latin "habilis" meaning capable. The structure mirrors many English opposites like "unhappy" or "uncertain."
English loves this simple "un-" trick: able/unable, certain/uncertain, known/unknown. Spotting the pattern helps you guess the meaning of words you’ve never seen before.
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