Natyashastra
प्रोद्वृत्तनिष्टब्धपुटा स्फुरदुद्वृत्ततारका । दृष्टिर्भयानाकात्यर्थं भीता ज्ञेया भयानके ॥ ४७॥
Bhayānakā: The Glance in which the eyelids are drawn up and fixed, and the eyeballs are gleaming and turning up is called Bhayānakā (terrible). It indicates a great fear and is used in the Terrible Sentiment.
english translation
prodvRttaniSTabdhapuTA sphuradudvRttatArakA । dRSTirbhayAnAkAtyarthaM bhItA jJeyA bhayAnake ॥ 47॥
hk transliteration by Sanscript