Darkening p. pr. & vb. n. : of Darken

Darkening n. : Twilight; gloaming.

Example:
How can I lessen the Darkening of the skin just above my upper lip after waxing it?

Taxonomy
free encyclopedia, search, free dictionary, vision loss, weakness, lesion, the eye, destruction, Two Trees of Valinor, fictional universe, Middle-earth, astronomical phenomenon, physical degradation, optical properties of glass, intensity, image of a star, edge, disambiguation pages.

Defination from the web:
Darkening (ophthalmology), vision loss or weakness that occurs without an apparent lesion affecting the eye. Darkening of Valinor, the destruction of the Two Trees of Valinor in in the fictional universe of J. R. R. Tolkien's Middle-earth ...