Collins Russian Dictionary 2nd Edition © HarperCollins Publishers 2000, 1997:
unwavering [ʌnˈweɪvərɪŋ] adj (faith) твёрдый*твёрд , непоколеби́мый/непоколеби́м (gaze) при́стальный*при́стален
* is used to mark translations which have irregular inflections. The Russian-English side of the dictionary gives inflectional information.