Natyashastra
अनेनैव क्रमेणैव पातनं स्यादधोमुखम् । भ्रुवोर्मूलसमुत्क्षेपात् भ्रुकुटी परिकीर्तिता ॥ १२१॥
Pātana (lowering)—lowering of eyebrows simultaneously or one by one. Bhrukuṭī (knitting)—raising the root of the eyebrows.
english translation
anenaiva krameNaiva pAtanaM syAdadhomukham । bhruvormUlasamutkSepAt bhrukuTI parikIrtitA ॥ 121॥
hk transliteration by Sanscript