Lack of ability is a term that can be used to describe a person's INABILITY to perform a task or complete a job. INCOMPETENCE, INEPTNESS, and INABILITY are all words that can be used to describe this lack of ability. INCOMPETENCE is a 12-letter word that means a lack of skill or knowledge in a particular area. INEPTNESS is a 9-letter word that means a lack of skill or ability in a particular area. INABILITY is also a 9-letter word that means the lack of capacity or capability to do something.