subaerial Syllabification: (sub·aer·i·al)Pronunciation: /ˌsəbˈe(ə)rēəl/Definition of subaerial adjective Geology existing, occurring, or formed in the open air or on the earth’s surface, not underwater or underground. Derivatives subaerially adverb subaerial in other Oxford dictionaries Definition of subaerial in the British & World English dictionary