upthrow Syllabification: (up·throw)Pronunciation: /ˈəpˌTHrō/ GeologyDefinition of upthrow verb [with object] (usually as adjective upthrown) displace (a body of rock) upward on one side of a fault relative to the other. noun an upward displacement of a body of rock on one side of a fault. upthrow in other Oxford dictionaries Definition of upthrow in the British & World English dictionary