Collins Russian Dictionary 2nd Edition © HarperCollins Publishers 2000, 1997:
synonymous [sɪˈnɔnɪməs] adj (fig)
synonymous (with)равноси́льный*равноси́лен ( +dat)
* is used to mark translations which have irregular inflections. The Russian-English side of the dictionary gives inflectional information.
Русский: