Natyashastra
शिरसो रेचनं यत्तु शनैस्तद् धुतमिष्यते । द्रुतमारेचनादेतद्विधुतं तु भवेच्छिरः॥२३॥
Dhuta and Vidhuta: A slow movement of the head is called the Dhuta, and when this movement is quick, it is called the Vidhuta.
english translation
ziraso recanaM yattu zanaistad dhutamiSyate । drutamArecanAdetadvidhutaM tu bhavecchiraH॥23॥
hk transliteration by Sanscript