Useful Set 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.

Old English settan, to put-down. As a color modifier, set implies a sunset-and-descending quality, the visual register of clear-sky western-horizon sunset-and-moonset descending-celestial-body atmospheric Rayleigh-scattered Belt-of-Venus orange-and-violet surfaces under descending-horizon-and-sunset light. Sits at the modifier-and-time end of the grid, parallel to rise and eve 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.