from dark (adj.);
the second element occurs also in crackmans a hedge, lightmans the day, etc.
1567 - A Caveat or Warening for Commen Cursetors, Vulgarely Called Vagabones,
see Example below
From: A Caveat or Warning for Common Cursetors, Vulgarly Called Vagabonds
By Thomas Harman
A Caveat for Cursetors