Firstly it indicates a person. If person: A low, abject, perfidious, mean person, secret enemy, whose aim is to harm; latent, mischievous figure, perverse and hostile person; lowly born, envious person. For the person don't have anything to gain, yet still wants to harm.

Reverse meaning: For the wicked the curse rebounds! Although wants to harm others, the person harms him/herself and the victim remains untouched.