DARKENING
Dark"en*ing, n.

Defn: Twilight; gloaming. [Prov. Eng. & Scot.] Wright.

DARKFUL
Dark"ful, a.

Defn: Full of darkness. [Obs.]

DARKISH
Dark"ish, a.

Defn: Somewhat dark; dusky.

DARKLE
Dar"kle, v. i. Etym: [Freq. of dark.]

Defn: To grow dark; to show indistinctly. Thackeray.

DARKLING
Dark"ling, adv. Etym: [Dark + the adverbial suffix -ling.]

Defn: In the dark. [Poetic]
So, out went the candle, and we were left darkling. Shak.
As the wakeful bird Sings darkling. Milton.