'sienna' originates from Italian, specifically the word 'terra di Siena,' where 'terra' meant 'earth' and 'Siena' is the name of a city in Italy.

'terra di Siena' was adopted into English as 'sienna,' referring to the pigment sourced from the region around Siena, Italy.

Initially, it meant 'earth from Siena,' but over time it evolved into its current meaning of 'a yellow-brown pigment.'