|Noah Webster's Dictionary|
1. (adv.) With imperfect light, clearness, or knowledge; obscurely; dimly; blindly; uncertainly.
2. (adv.) With a dark, gloomy, cruel, or menacing look.
Int. Standard Bible Encyclopedia
dark'-li: The word occurs in 1 Corinthians 13:12, "For now we see in a mirror, darkly," in translation of the words en ainigmati, the Revised Version, margin "in a riddle." The contrast is with the "face to face" vision of Divine things in eternity. Earth's best knowledge is partial, obscure, enigmatic, a broken reflection of the complete truth ("broken lights of Thee").
Darkly (1 Occurrence)
1 Corinthians 13:12 For now we see through a glass, darkly; but then face to face: now I know in part; but then shall I know even as also I am known. (KJV ASV BBE WBS)