I didn't take rumi's advice and look it up in an encyclopedia. I looked it up in the dictionary. Just now.
http://dictionary.reference.com/search?q=dervish
For the record then, all of the definitions given:
<li>A member of any of various Muslim ascetic orders, some of which perform whirling dances and vigorous chanting as acts of ecstatic devotion.
<li>One that possesses abundant, often frenzied energy.
<li>
Word History: The word dervish calls to mind the phrases howling dervish and whirling dervish. Certainly there are dervishes whose religious exercises include making loud howling noises or whirling rapidly to induce a dizzy, mystical state. But a dervish is really the Muslim equivalent of a monk or friar, for the Persian word darvsh, the ultimate source of dervish, means “religious mendicant.” The word is first recorded in English in 1585.
<li>One of the fanatical followers of the Mahdi, in the Sudan.
<li>A Turkish or Persian monk, especially one who professes extreme poverty and leads an austere life.
<li>An ascetic Muslim monk; a member of an order noted for devotional exercises involving bodily movements
So there it is, and rumi, oh dear, none of them mention the word "student". I won't rub it in too hard though, because I'm a nice guy.