unable to
/ˌʌnˈeɪ.bəl tuː/adjective phrase★Intermediate
general
Not having the ability or capacity to do something
The machine was unable to process the request.
The machine couldn't handle the request.
He was unable to finish the project on time.
He couldn't complete the project by the deadline.
💡
Often used to express inability due to physical, mental, or situational constraints.
Collocations
unable to doincapable of performing an actionunable to attendincapable of being presentunable to understandincapable of comprehending
Synonyms
Antonyms
Related Phrases
able tophrase
capable of doing something
incapable ofphrase
not having the ability to do something
💡Pro Tip
Formal vs. Informal Usage
'Unable to' is more formal than 'can't' or 'couldn't'. Use it in professional or written contexts.
⚡Gold Rule
Correct Usage
Always follow 'unable to' with a verb in its base form (infinitive).
📖Word Origin
From 'un-' (not) + 'able' (capable) + 'to' (infinitive marker)
📝Usage Notes
Commonly used in formal and informal contexts to describe lack of ability or capacity.
Word Breakdown
un-
not
prefixable
capable
rootto
infinitive marker
particleEnglish Dictionary