Princess is a title of royalty used for the consort of a Prince or for the daughter of a King or Queen. La Moor was the Princess of the Madronans. (SG1: "Touchstone")
Shyla was the Princess of Terella. (SG1: "Need")
Mara was the Princess of the Lord Protector's Planet. (SGA: "The Tower")
Harmony was a Princess of her planet, along with her sisters Flora and Mardola. (SGA: "Harmony")