aṅguṣṭha-parimāṇakaḥ

iti-thus; abhidhyayatah-while thinking; nasa-vivarat-from the nostrils; sahasa-all of a sudden; anagha-O sinless one; varahatokah-a minute form of Varaha (a boar); niragat-came out; aṅgustha-upper portion of the thumb; parimanakah-of the measurement.