fenestra

noun, plural fe·nes·trae [fi-nes-tree] /fɪˈnɛs tri/.

1. Anatomy, Zoology. a small opening or perforation, as in a bone, especially between the middle and inner ear.
2. Entomology. a transparent spot in an otherwise opaque surface, as in the wings of certain butterflies and moths.
3. Architecture. a windowlike opening.

noun plural -trae (-triː)

1. biology a small opening in or between bones, esp one of the openings between the middle and inner ears
2. zoology a transparent marking or spot, as on the wings of moths
3. architect a window or window-like opening in the outside wall of a building

n. pl. fe•nes•trae (-trē′)

1. A small anatomical opening, often closed by a membrane.
2. The opening in a bone made by surgical fenestration.
3. A specialized opening, as in a surgical instrument.