autonomic Syllabification: (au·to·nom·ic)Pronunciation: /ˌôtəˈnämik/Definition of autonomic adjective [attributive] chiefly Physiology involuntary or unconscious; relating to the autonomic nervous system. Origin: mid 19th century (in the sense 'self-governing'): from autonomy + -icautonomic in other Oxford dictionaries Definition of autonomic in the British & World English dictionary