Useful Nereid 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 Νηρηΐς, sea-nymph-daughter-of-Nereus. As a color modifier, nereid implies a sea-nymph-and-Aegean-foam quality, the visual register of Hellenic-Nereid-and-Aegean-sea-nymph hand-sea-nymph-and-Aegean-foam Hellenic-Nereid-and-Aegean-sea-nymph-and-Poseidon-court nereid-and-sea-nymph-and-Aegean-foam surfaces under Hellenic-Nereid-and-Aegean-sea-nymph-and-Poseidon-court Aegean-island-and-rocky-cove sea-nymph-light. Sits at the modifier-and-myth end of the grid, parallel to nymph and dryad 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.