'reddish-brown' originates from the combination of 'red' and 'brown', where 'red' meant 'the color of blood' and 'brown' meant 'a dark color'.

'reddish-brown' evolved from the Old English words 'rēad' (red) and 'brūn' (brown), eventually forming the modern English compound adjective 'reddish-brown'.

Initially, it meant 'a color between red and brown', and this meaning has largely remained the same in modern usage.