'blue-yellow' originates from the combination of the words 'blue' and 'yellow', where 'blue' meant 'the color of the sky' and 'yellow' meant 'the color of ripe lemons'.

'blue-yellow' was not a common term in medieval English but has been used in modern times to describe a specific color combination.

Initially, it was used to describe a mix of blue and yellow pigments, but over time it evolved into its current meaning of a specific color hue.