Definition of "fenestration"

(architecture) The arrangement of windows and similar openings in a building.  examples

(surgery, anatomy) An opening in the surface of an organ etc; the surgical creation of such an opening, especially one in the bony part of the inner ear made to improve hearing.  examples

(surgery, anatomy) An opening that occurs naturally or is created surgically, as through a biological membrane.  examples

(botany) Either a translucent area in a structure such as a leaf or flower petal, or an opening in a structure.  quotations  examples

(nautical) The practice of placing holes in the rudder of a ship to reduce the work required to move the rudder while preserving its ability to steer the ship.  examples