/ ˈdɜːvɪʃ; NAmE ˈdɜːrvɪʃ/ noun
a member of a Muslim religious group whose members make a promise to stay poor and live without comforts or pleasures. They perform a fast lively dance as part of their worship :
He threw himself around the stage like a whirling dervish.
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WORD ORIGIN
from Turkish derviş , from Persian darvīš poor, (as a noun) religious mendicant.