Darkling

Part of speech: adverb (adv.)

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

Part of speech: participle (p.)

1. Becoming dark or gloomy; frowing. His honest brows darkling as he looked towards me. Thackeray.

2. Dark; gloomy. "The darkling precipice." Moore.