What does unable mean?
Unable means lacking the ability, power, or means to do something. It is a widely used adjective in standard British and American English and is especially common when describing a person’s physical limitation, a lack of resources, or a circumstance that prevents action. Its standard construction is “unable to” followed by an infinitive verb: “The team was unable to finish the project on time.” The word can describe either a general lack of capacity, as in “unable to swim,” or a specific circumstance preventing action, as in “unable to attend.” Although it often appears in formal writing, it is equally natural in everyday speech. Unable is especially useful because it communicates both limitation and dependence on an external condition without suggesting that the person or situation lacks value or importance. It is a clear alternative to more specialized phrases such as “not capable of.”
adjectiveLacking the ability, power, or means to do something. It is commonly followed by “to” and an infinitive verb.
- Lacking the physical, mental, or practical capacity to do something.
- Not being in the circumstances or possessing the means to act in a particular way.
"The heavy snow made it impossible for the hikers to continue, leaving them unable to reach the shelter."
"The locked gate left us unable to enter the garden."
"She was unable to attend the meeting because of a scheduling conflict."
Unable turns ability off at the switch: it means “not able,” and it is almost always followed by “to” plus an infinitive.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of unable
Unable entered Middle English from an Old French or Anglo-Norman form ultimately based on Latin in-, meaning “not,” and habilis, meaning “able” or “capable.” The word developed into its familiar English meaning of “lacking ability or capacity.” Its grammatical use with “to” and an infinitive reflects the established construction “unable to do” something. Related forms such as ability, disable, and disability come from the same broader Latin root associated with being able or being made capable.
How unable is actually used
Unable is normally followed by “to” and an infinitive, as in “unable to reach.” It is common in formal and informal English, although constructions such as “unable for” are less usual and can sound formal or awkward.
Easily confused with unable
Unable describes a lack of ability or capacity, whereas unavailable means that something is not accessible, available, or free at a particular time.