That can be brightened.

plural of brightener

present participle of brighten

An instance of becoming brighter.

One who or that which brightens. / A chemical agent that absorbs ultraviolet and violet light and re-emits blue light by fluorescence, used to make fabric or paper look whiter.

(transitive) To make bright or brighter in color. / (transitive) To make illustrious, or more distinguished; to add luster or splendor to

simple past tense and past participle of brighten

Third-person singular simple present indicative form of brighten

plural of brightening

(intransitive, said of the weather) To become brighter / (transitive) To make cheerful.