Sonorous Neptune Indigo

Latin sonōrus, resounding — derived from sonus (sound). As a color modifier, sonorous implies a saturated-and-richly-vibrating quality where the hue carries the deep-resonance visual register of a cathedral-organ-pipe low-note. Sits at the bold-and-resonant end of the grid, parallel to resonant and deep in usage.

Latin Neptunus, Roman-god-of-sea-and-eighth-planet. As a color modifier, neptune implies a Roman-god-of-sea-and-deep-blue-eighth-planet quality, the visual register of Roman-Neptune-and-Voyager-2-deep-blue hand-Roman-god-of-sea-and-deep-blue-eighth-planet Roman-Neptune-and-Voyager-2-deep-blue-and-Trevi-Fountain neptune-and-Roman-god-of-sea surfaces under Roman-Neptune-and-Voyager-2-deep-blue-and-Trevi-Fountain Voyager-2-flyby-and-Trevi-Fountain deep-blue-planet-light. Sits at the modifier-and-zodiac end of the grid, parallel to uranus and saturn in usage.

Indigofera tinctoria, the South Asian legume whose leaves yield the deep blue dye that has clothed humanity for at least four thousand years — Egyptian linen, Mayan textile, the slave-grown plantations of Carolina. The color refers to a freshly indigo-dyed cotton thread: a saturated, slightly violet-shifted deep blue with the slight lustre of a fiber surface oxidized in air. Deeper than cobalt, cooler than royal.