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tri·lith·on(trī-lĭth′ŏn, trī′lĭ-thŏn′) also tri·lith (trī′lĭth)
A prehistoric structure consisting of two large stones set upright to support a third on their tops, found especially in Europe.
[Greek, neuter of trilithos, having three stones : tri-, tri- + lithos, stone.]
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