Open Keel Teal

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.

Old Norse kjölr, keel. As a color modifier, keel implies a longitudinal-bottom-spine-of-ship quality, the visual register of Tall-Ship-and-Royal-Navy-Keel hand-laid longitudinal-bottom-spine timber-and-iron-keel tall-ship-and-frigate maritime-architecture surfaces under hull-and-keel maritime hull-bottom light. Sits at the modifier-and-nautical end of the grid, parallel to hull and spar 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.