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1610s, "action of excavating," from Latin excavationem (nominative excavatio) "a hollowing out," noun of action from past participle stem of excavare (see excavate).
excavation ex·ca·va·tion (ěk'skə-vā'shən)n.
A natural cavity, pouch, or recess.
A cavity formed artificially or as the result of a pathological process.