ptilosis

Etymology
Borrowed from, from the.

Noun

 * 1)  The appearance or study of feathers on a bird, including factors such as their texture or shape.
 * 2)  Loss of the eyelashes, due to ulceration or other damage to the follicles.
 * 1)  Loss of the eyelashes, due to ulceration or other damage to the follicles.

Usage notes
In ornithology, ptilosis refers to the properties of the feathers themselves, while pterylosis refers to the arrangement of those feathers and how they are implanted in the skin.

In medicine, ptilosis refers specifically to the eyelashes, while madarosis can also apply to the eyebrows, and alopecia can apply to hair loss in any part of the body.