In saMskR^itam the word shiva means auspicious, prosperous (maN^gaLam). The Lord who is called pashupati, Asutosha being the Supreme that can not be measured by the thoughts, appears to the one who worships as the God graceful, blissful and nurturing. Its auspicious and graceful forms and names are invoked by the worshiper for the upliftment of oneself.
In thamiz it refers to shiva - civappu - chemporuL meaning the Perfect Being. The God staying in a state blissful, enjoying in Its Own Self eternally, without any flaws is the Supreme Lord shiva. The Perfection is the completeness - there is nothing external that is required to make the Self blissful. In this context it would be worthwhile to contemplate on the mantra shivatarAya.