1. The production and operation of airplanes and other machines that fly: The three women, whose life stories were told in the film about early aviation, lived in a city near where Jane grew up.
2. Etymology: from Latin avis, "bird" + -ationem, "an action, a process."

A sleeping sickness or a sleep-like condition: Raymond, in his old age, often has lethargus during the day and so he takes a nap in most of the afternoons.

1. The art of photographing astronomical objects and events for astronomical studies>
2. The photography of stars and other celestial objects.
3. The use of photographs to record extraterrestrial objects in order to study their surface features, positions, motions, radiation, and spectra.

Congenital absence of eyelids, with the skin passing continuously from the forehead onto the cheek over a rudimentary or non-functional eye: The cryptophthalmos is classified into three types: complete, incomplete and abortive.

Cryptophthalmos usually occurs on both sides and occurs in association with several other malformations collectively referred to as Fraser syndrome.