able vs unable

able and unable both are adjectives.

Word	Noun	Adjective	Verb	Adverb
able	No	Yes	No	No
unable	No	Yes	No	No

able (adjective)	unable (adjective)
(usually followed by `to') having the necessary means or skill or know-how or authority to do something	(usually followed by `to') not having the necessary means or skill or know-how
having inherent physical or mental ability or capacity	lacking in power or forcefulness
have the skills and qualifications to do things well	(usually followed by `to') lacking necessary physical or mental ability
having a strong healthy body