steadfast in purpose or intention; unalterable, unyielding
not capable of being affected or moved in feeling; impassive
not liable to be removed; permanent in place or tenure; fixed
incapable of being physically moved; fixed
that which can not be moved; something which is immovable
resolute, unfaltering, unwavering
Having no errors or loopholes; unassailable
Not able to be shaken; firm, solid