Natyashastra
शनैराकम्पनादूर्ध्वमधश्चाकम्पितं भवेत् । द्रुतं तदेव बहुशः कम्पितं कम्पितं शिरः ॥ १९॥
Ākampita: Moving the head slowly up and down is called the Ākampita. Kampita: When the movements in the Ākampita head are quick and copious the same is called Kampita.
english translation
zanairAkampanAdUrdhvamadhazcAkampitaM bhavet । drutaM tadeva bahuzaH kampitaM kampitaM ziraH ॥ 19॥
hk transliteration by Sanscript