Why is blue called blue?

Answer and Explanation:

The modern English word blue comes from Middle English bleu or blewe, from the Old French bleu, a word of Germanic origin, related to the Old High German word blao (meaning shimmering, lustrous). In heraldry, the word azure is used for blue.

English also gets some of its words from French, and blue is one of them. In Old French (one of the vulgar Latin dialects whose height was between the 9th and 13th centuries AD) blue was written bleu and blew and meant a variety of things including the color blue.

Hope this helps! :)