Definition of a Sufi:

One who has mastered his soul, cleansed and purified it from vices, adorned it with virtues, severed all bonds attaching his heart to the worlds, turned inwardly as well as outwardly towards the divine presence, established his heart in the attitudes of unification and single hearted concentration and his outer form in that to service of God, exalted is He, as is the attribute of servants.