Trilithon
Pronunciation : Tril"i*thon (tr?l"?*th
Part of Speech : n.;
Etymology : [NL., fr. Gr.Tri- ) + (Arch?ol.)
Definition : Defn: A monument consisting of three stones; especially, such a monument forming a kind of doorway, as among the ancient Celts.
pl. Trilithons
Source : Webster's Unabridged Dictionary, 1913