auburn
Synonym discussion
Sense: adjective/1
For this sense, auburn is mainly a hair-colour word. Reddish-brown gives the colour idea directly and can describe many things, so it is broader and less tied to hair. Chestnut is also common for hair, but it often suggests a deeper brown with less visible red. Coppery points to a brighter orange-red shine and can feel more vivid than auburn. If a story says a girl has auburn hair, the image is usually soft and warm. If it says coppery hair, the colour sounds brighter. You might describe a horse as chestnut, but people more often describe a person's curls as auburn.
Etymology
Auburn came into English from an older French form, and its history is unusual because the word did not originally mean this red-brown colour. Earlier stages were linked to a Latin word meaning a pale or off-white shade. In English, the form gradually shifted and later became associated with brown and red tones, which led to the modern meaning used especially for hair.