Useful Ether Teal

Latin ūsus, use — adjectival suffix -ful. As a color modifier, useful implies a clear-and-purpose-serving quality where the hue carries the visual register of helpful-and-supporting design-element. Sits at the crisp-and-functional end of the grid, parallel to practical and serviceable in usage.

Greek αἰθήρ, upper-air-or-quintessence. As a color modifier, ether implies a luminiferous-and-pure-upper-air quality, the visual register of Aristotelian-quintessence-and-luminiferous-ether hand-luminiferous-and-pure-upper-air Aristotelian-quintessence-and-luminiferous-and-Newtonian ether-and-luminiferous-and-pure-upper-air surfaces under Aristotelian-quintessence-and-luminiferous-and-Newtonian celestial-spheres-and-natural-philosophy upper-air-light. Sits at the modifier-and-cosmic end of the grid, parallel to plasma and nebula in usage.

Anas crecca, the small dabbling duck whose male in breeding plumage sports a chestnut head crossed by a glossy green-blue stripe. The color refers to that stripe — the iridescent panel just behind the eye: a saturated, slightly muted blue-green with the optical depth of structural color rather than pigment. Cooler than cypress, warmer than cerulean, with the ornithological specificity of a color named for one feather of one bird.