Sianni is a modern American name of uncertain origin, usually explained as an elaboration of the Welsh Sian, a form of Jane that means "God is gracious", or as a respelling of Sienna with the double n of Gianni. It is used mainly in African American families and has the melodic -i ending of Sanai and Saniyah. Sianni appeared only rarely until recently, then jumped from number 4643 in 2023 to number 1629 in 2025, its best rank so far.