The color azure ultimately takes its name from the intense blue mineral lapis lazuli. Lapis is the Latin word for "stone" and lazuli is the genitive form of the Medieval Latin lazulum, which is taken from the Arabic لازورد lāzaward, itself from the Persian لاژورد lāžaward, which is the name of the stone in Persian and also of a place where lapis lazuli was mined.
The name of the stone came to be associated with its color. The French azur, the Italian azzurro, the Polish lazur, Romanian azur and azuriu, the Portuguese and Spanish azul, Hungarian azúr, and the Catalan atzur, all come from the name and color of lapis lazuli.
The word was adopted into English from the French, and the first recorded use of it as a color name in English was in 1374 in Geoffrey Chaucer's work Troilus and Criseyde, where he refers to "a broche, gold and asure" (a brooch, gold and azure).