epilithic Syllabification: (ep·i·lith·ic)Pronunciation: /ˌepəˈliTHik/Definition of epilithic adjective Botany (of a plant) growing on the surface of rock. Origin: early 20th century: from epi- 'upon' + Greek lithos 'stone' + -icepilithic in other Oxford dictionaries Definition of epilithic in the British & World English dictionary