Sanskrit Verse
निष्कम्पे नित्यपूर्णे निरवधिपरमानन्दपीयूषरूपे
निर्लीनानेकमुक्तावलिसुभगतमे निर्मलब्रह्मसिन्धौ ।
कल्लोलोल्लासतुल्यं खलु विमलतरं सत्त्वमाहुस्तदात्मा
कस्मान्नो निष्कलस्त्वं सकल इति वचस्त्वत्कलास्वेव भूमन् ॥ ४ ॥
Audio Link
(Courtesy Shri. Sankararama Sharma – Ref
https://www.dropbox.com/s/nvk97yq7sqt87g4/Sloka%204.mp3?dl=0
Meaning in Tamil

Meaning in English
Brahman is akin to the mighty ocean, changeless, ever full with the nature of unlimited nectarine bliss. Like many pearls in the ocean, innumerable liberated souls are absorbed in this Brahmic bliss and hence it is extremely resplendent. Just like the waves rise in the ocean, it is said that Shuddha Satwa form has risen from the Brahman. You, here in Guruvayur is that Satwa form. Hence it is appropriate to call Lord Guruvayurappan as Poorna Avataar (Nishkalaa) even though some may argue that if You have a form then you are Ansha Avataar (Sakalaa).
English Transliteration
NiShkampe nityapuurNe niravadhiparamaanandapiiyuuSharuupe
nirliinaanekamuktaavalisubhagatame nirmalabrahmasindhau .
kallOlOllaasatulyaM khalu vimalataraM sattvamaahustadaatmaa
kasmaannOniShkalastvaM sakala iti vachastvatkalaasveva bhuuman..4
Meaning of the Sanskrit Words
निष्कम्पे – (in the) vibrationless (changeless)/motionless
नित्यपूर्णे – नित्य पूर्ण – (and in the) ever full
निरवधिपरमानन्दपीयूषरूपे – निरवधि परमानन्द पीयूष रूपे – unlimited, bliss, nectarine, personified (form)
निर्लीन-अनेक-मुक्तावलि-सुभगतमे -liberated/unaffected, several, pearl necklace/ string of pearls, prosperity/loveliness
(in which) many liberated ones having merged and hence is extremely resplendent (or resplendent because of many pearls in the ocean)
निर्मल-ब्रह्म-सिन्धौ – in the pure ocean of Brahman
कल्लोल-उल्लास-तुल्यं- waves, happiness/joy, like (like waves rising)
खलु विमलतरं सत्त्वम्-आहु: – so then, pure (state of being stainless), satwam, invoke
[(so) indeed (Thy form) of extremely pure Shuddha Satwa it is said (to have risen from Brahman)]
तत्-आत्मा – that form of Thine
कस्मात्-न निष्कल: – त्वं – why not it be called Nishkala (undivided /seedless/without any parts (or without any kalaa or Purn-avataara
सकल इति वच: – total, this, word/term
त्वत्-कलासु-एव – you, time defined, only
[(is for Thy (other) part incarnations only)]
भूमन् – abundance (oh infinite one)