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1870 in the anatomical sense, noun of action from Latin fenestrare, from fenestra "window, opening for light," perhaps from Etruscan. Meaning "arrangement of windows" is from 1846. Related: Fenestrated.
fenestration fen·es·tra·tion (fěn'ĭ-strā'shən)
An opening in the surface of a structure, as in a membrane.
The surgical creation of such an opening.
The surgical creation of an artificial opening in the bony part of the inner ear to improve or restore hearing.