a small membrane-covered opening (especially one in the bone between the middle and inner ear)
a small opening such as a hole in a bone, or a transparent window in a moth's wing
In cheilostomate ovicells, an uncalcified area in the ectooecium through which the endooecium is displayed (after Ryland & Hayward, 1977) (Cf. tabula). Also used for an uncalcified opening in the frontal wall with direct communication from the external environment to the space between the calcified frontal wall and the frontal membrane. In earlier papers, fenestra may be used in the sense of fenestrula. Compare window.
A fenestra is a natural hole or opening in a bone. The skull has many fenestra.
an opening. The plural is fenestrae.
In nematodes: A window or transparent spot; in some Heteroderidae, a thin-walled region of the vulval cone. (Pl. fenestrae.) ( 14)