megalithicPronunciation: /mɛgəˈlɪθɪk/Definition of megalithic adjective Archaeology relating to or denoting prehistoric monuments made of or containing megaliths: massive megalithic monuments (often Megalithic) relating to or denoting prehistoric cultures characterized by the erection of megalithic monuments: the resident Megalithic peoplesOrigin: mid 19th century: from mega- 'large' + Greek lithos 'stone' + -icmegalithic in other Oxford dictionaries Definition of megalithic in the US English dictionary