The British use of “green” to mean “envious” originates from ancient associations between the color green and emotions like jealousy and envy. This connection dates back to at least Shakespearean times, as seen in Othello (1603), where Iago refers to jealousy as the “green-eyed monster.” In modern British English, saying someone is “green with envy” remains a common idiom, meaning they are intensely jealous.