Spotless Throb Lagoon

Old English spott (spot) plus suffix -less. As a color modifier, spotless implies a clear-and-unmarked quality where the hue carries no contaminating speck or stain. Sits at the crisp-and-clean end of the grid, parallel to pristine and unblemished in usage.

Middle English throbben, to-beat-strongly. As a color modifier, throb implies a pulsing-and-beating-and-rhythmic quality, the visual register of racing-pulse-and-temple-throb hand-pulsing-and-beating-and-rhythmic racing-pulse-and-temple-throb-and-heartbeat throbbed-and-pulsing-and-beating-and-rhythmic surfaces under racing-pulse-and-temple-throb-and-heartbeat fevered-and-quickened-and-rhythmic candlelit-bedside-light. Sits at the modifier-and-mood end of the grid, parallel to pang and pulse 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.