tāsu - in that; avātsīt - resided; sva - own; sṛṣṭāsu - in the matter of creation; sahasram - one thousand; parivatsarān - years of His measurement; tena - for that reason; nārāyaṇaḥ - the Personality of Godhead named Nārāyaṇa; nāma - name; yat - because; āpaḥ - water; puruṣa-udbhavāḥ - emanated from the Supreme Person.

That Supreme Person is not impersonal and therefore is distinctively a nara, or person. Therefore the transcendental water created from the Supreme Nara is known as nāra. And because He lies down on that water, He is known as Nārāyaṇa.