Collins Russian Dictionary 2nd Edition © HarperCollins Publishers 2000, 1997:
ambitious [æmˈbɪʃəs] adj (see n) честолюби́вый/честолюби́в ; амбицио́зный*амбицио́зен
* is used to mark translations which have irregular inflections. The Russian-English side of the dictionary gives inflectional information.