Useful Wane 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 wanian, to lessen. As a color modifier, wane implies a waning-moon-and-fading quality, the visual register of waning-moon-and-late-summer gradually-diminishing-and-receding waning-and-fading celestial-body-and-seasonal-light surfaces under waning-and-receding lunar-and-seasonal light. Sits at the modifier-and-time end of the grid, parallel to phase and eld 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.