Monks describes the Jedi more accurately than it does the Sith in my opinion. At different times in their history each organization has strayed from being a monk order to a cult and back again.
Generally, monks are individuals who forsake worldly gain and pleasure to pursue a life of service and contemplation of the divine. The Sith are the antithesis of that: they exploit a divine power for worldly gain and pleasure.
One thing that I don’t think is thought about enough is how much sex Sith would realistically be having. Other than maybe Maul, who was raised as kind of a murder monk, I don’t think the sith could be classified as monks in the slightest.
