Sienna is taken from the Tuscan city of Siena and from the warm reddish-brown pigment called terra di Siena, so the name is usually read as "earth of Siena" or simply as the color "reddish brown". British actress Sienna Miller gave it visibility in the 2000s. Sienna ranked number 621 in 2000 and number 139 in 2024, then jumped to number 94 in 2025, its first appearance in the US top 100.