Unable is an adjective meaning not able — unable to attend. Enable is a verb meaning to make able, or to switch on — enable the setting. The prefixes do the work: un- negates, en- makes. The opposite of enable is disable, not unable.
The core difference
- unable — adjective: lacking the ability or means. I was unable to reach her, unable to pay.
- enable — verb: to give the ability or means; to switch a function on. The grant enabled them to expand, enable notifications.
The tell
Unable describes a person or thing and always pairs with to: unable to sleep. Enable has an object — someone or something is enabled — and a family: enabled, enabling, enabler. The switch-on sense has a clean opposite, disable; unable is never a verb and never a setting.
In use
- unable — I was unable to find the file. Unable to attend, she sent apologies.
- enable — The loan enabled them to expand. Enable two-factor login in settings.
Common slips
- I was enable to come → I was unable to come
- unable cookies in your browser → enable cookies in your browser
Unable is a state; enable is an action; disable undoes it.
Where the words come from
Both are able with a prefix, and able comes from Latin habilis, "handy, fit". Un- is the Old English negative; en- is the French causative prefix meaning "make", as in enlarge and enrich. Enable is recorded from the fifteenth century; the computing sense of turning a feature on dates from the twentieth.
