noun

• (countable and uncountable) The clear blue colour of the sky; also, a pigment or dye of this colour.
  "In robes of azure."
• (heraldry) A blue colour on a coat of arms, represented in engraving by horizontal parallel lines.
  "Berington of Chester (on the authority of Harleian manuscript No. 1535) is said to bear a plain shield of azure. Personally I doubt this coat of arms […]"
• (poetic) The unclouded sky; the blue vault above.
  "Not like those steps / On heaven's azure."

adj

• (heraldry) In blazon, of the colour blue.
  "‘I forget your coat of arms.’ ‘A human foot d’or, in a field azure; the foot crushes a serpent rampant whose fangs are imbedded in the heel.’"

verb

• (transitive) To colour blue.
  "Our readers are aware that much of the sugar sold in many countries goes through an azuring treatment; blue is added to granulated sugar with the view of making it appear whiter than it actually is."