From melas (black). Blackness, darkness. Related to the imagery of moral and spiritual darkness that contrasts with the light of God's truth.
Scripture consistently uses darkness as a metaphor for sin, ignorance, and separation from God. 'God is light; in him there is no darkness at all' (1 John 1:5). The ultimate judgment is described as 'outer darkness' (Matthew 25:30). But the gospel is the message that light has invaded the darkness, and the darkness has not overcome it (John 1:5).