Blu is a pared-down spelling of Blue, the English color word that came into Middle English from Old French bleu and ultimately from a Germanic root, so it simply means "blue". As a first name it belongs to the modern wave of color and nature names like Sky, Onyx and Ash, and the short spelling gives it a cooler look. Blu stood at number 10550 in 2000, reached number 2656 in 2021 and stands at number 2890 in 2025 with 43 births.