Webster's Revised Unabridged Dictionary · 1913

Darkly

Darkly , adverb

1.
With imperfect light, clearness, or knowledge; obscurely; dimly; blindly; uncertainly.
What fame to future times conveys but darkly down. — Dryden
so softly dark and darkly pure. — Byron
2.
With a dark, gloomy, cruel, or menacing look.
Looking darkly at the clerguman. — Hawthorne