MEGALITH
megalith, megalithic structure
(noun) memorial consisting of a very large stone forming part of a prehistoric structure (especially in western Europe)
Source: WordNet® 3.1
Etymology
Noun
megalith (plural megaliths)
(archaeology) A construction involving one or several roughly hewn stone slabs of great size.
A large stone used in such a construction.
Source: Wiktionary
Meg"a*lith, n. Etym: [Mega- + -lith; cf. F. mégalithe.]
Definition: A large stone; especially, a large stone used in ancient
building.
– Meg`a*lith"ic, a.
Source: Webster’s Unabridged Dictionary 1913 Edition