Ten great warrior sons were sired by Raudrāśva (Raudraswa), the third son of King Puru, to apsarā (apsara; celestial nymph) Miśrakeśī (Misrakesi). Ṛceyu (Richeyu) was the foremost of them and later became known as one of the most powerful kings of the lineage. He was invincible in the battlefield. One meaning of the Sanskrit word dharṣaṇa (dharshana) and its derivative dhṛṣṭi (dhrishti) is ‘to beat’ or ‘to conquer’. The word anādhṛṣṭi (anadhrishti) is an adjective negating this essence and implying the meaning ‘unconquerable’. It is because of this reason that this adjective has been associated with the unbeatable king Ṛceyu as an epithet in Mahābhārata (Mahabharata) –

anādhṛṣṭirabhūtteṣāṃ vidvān bhuvi tathaikarāṭ
ṛceyuratha vikrānto devānāmiva vāsavaḥ.

Nīlakaṇṭha (Nilakantha), the annotator of Mahābhārata, comments on this verse –

ekarāṭ advitīyo rājā; ataeva tasya enāpi dharṣaṇāsambhāvāt sa anādhṛṣṭi stadākhyaścābhūt. [See. Ṛceyu]