UNA'BLE, adjective 1. Not able; not having sufficient strength or means; impotent; weak in power, or poor in substance. A man is unable to rise when sick; he is unable to labor; he is unable to support his family or to purchase a farm; he is unable for a particular enterprise. 2. Not having adequate knowledge or skill. A man is unable to paint a good likeness; he is unable to command a ship or an army.
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI