huge prehistoric stone, 1853, back-formation from megalithic.
Entries linking to megalith
megalithic adj.
"consisting of very large stones," 1836, from mega- "large" + lithos "stone" (see litho-) + -ic. Now usually in reference to large stones in more or less their natural form, set up in ancient times in menhirs, dolmens, rings, etc., especially in Western Europe but also in North Africa and India.