Emily Dickinson Lexicon

AZ'URE, n. [azh'ur.]

1. The fine blue color of the sky. This word was formerly applied to the lapis lazuli, and the color prepared from it. But it is now applied to the blue extracted from cobalt, though somewhat a different color; the blue of the lapis is called ultramarine. Azure is applied also to the blue glass made of the oxyd of cobalt and vitrifiable substances reduced to fine powder. In large masses it is called smalt. Encyc.
2. The sky, or azure vault of heaven.
3. In heraldry, a blue color in coats of all persons under the degree of baron. – Jones.