Heartening Fall Lagoon

Old English heorte (heart) — present-participle of hearten. As a color modifier, heartening implies a clear-and-uplifting-and-encouraging quality where the hue carries the visual register of cheerful-encouraging color-tone. Sits at the crisp-and-cheerful end of the grid, parallel to welcoming and cheerful in usage.

Old English feallan, to fall / autumn. As a color modifier, fall implies an autumn-leaf-and-harvest quality, the visual register of New-England-and-English-autumn deciduous-leaf-fall maple-and-oak-and-beech autumnal-orange-and-crimson surfaces under Northern-Hemisphere autumn raking light. Sits at the modifier-and-time end of the grid, parallel to yule and reap in usage.

A shallow body of saltwater partially or fully enclosed by a barrier — coral atoll lagoons in the Pacific, Venice's Laguna Veneta, the Florida Keys' backcountry. The color refers to the average reflectance of a calm tropical lagoon at midday: a saturated, slightly muted blue-green with the optical clarity of shallow water over white sand. Brighter than reef, cooler than aquamarine, with the postcard weight of a Pacific atoll seen from above.