cerulean

Deep sky blue; the color of a clear sky.

• (no common derivatives)

• cerulean sky
• cerulean sea
• cerulean blue
• cerulean waters

1. 1.The cerulean waters of the Mediterranean stretched unbroken to the horizon. (deep sky blue)
2. 2.She painted the ceiling cerulean to bring the feeling of open sky indoors. (sky-blue color)

• azure/ˈæʒər/— bright blue, poetic
• cobalt/ˈkoʊbɔːlt/— deep blue
• sapphire/ˈsæfaɪər/— deep blue, jewel-like

from Latin "caeruleus" (dark blue, sky-colored) — possibly related to "caelum" (sky, heaven) — the color of the heavens