Siress Uri is the wife of Quorum member Sire Uri.
According to Sire Uri, his wife never made "the voyage" (TOS: "Saga of a Star World"). It is most likely that Siress Uri was either left behind in the exodus from the Twelve Colonies, or killed in the attack on the Colonies.
Sire Uri's apparent lack of concern or mourning suggests that his wife's loss means little to him. When visited by Apollo and Boomer, Sire Uri is surrounded by aesthetically pleasing females on the Rising Star.
According to the novelization, Apollo recalls Siress Uri being a woman of great virtue and patience.