Collins Russian Dictionary 2nd Edition © HarperCollins Publishers 2000, 1997:
loathsome [ˈləuðsəm] adj отврати́тельный*отврати́телен , омерзи́тельный*омерзи́телен
* is used to mark translations which have irregular inflections. The Russian-English side of the dictionary gives inflectional information.
Русский: