Open Nadir Lagoon

Old English open, unobstructed — used as a color modifier since the eighteenth century for hues that read as airy or uncrowded. Open blue, open green: moderate saturation combined with optical spaciousness, the slight visual breath of a hue that doesn't crowd the surface it covers. Sits at the crisp-bucket center alongside clear.

Arabic naẓīr, opposite-of-zenith. As a color modifier, nadir implies a downward-pointing-and-low-point quality, the visual register of celestial-sphere-and-downward-Nadir hand-downward-pointing-and-low-point celestial-sphere-and-downward-and-Nadir-pole nadir-and-downward-pointing-and-low-point surfaces under celestial-sphere-and-downward-and-Nadir-pole astronomical-and-celestial-mechanics downward-axis-light. Sits at the modifier-and-cosmic end of the grid, parallel to zenith and axis in usage.

A shallow body of saltwater partially or fully enclosed by a barrier — coral atoll lagoons in the Pacific, Venice's Laguna Veneta, the Florida Keys' backcountry. The color refers to the average reflectance of a calm tropical lagoon at midday: a saturated, slightly muted blue-green with the optical clarity of shallow water over white sand. Brighter than reef, cooler than aquamarine, with the postcard weight of a Pacific atoll seen from above.