Heavy Fall Forest

Old English hefig, weighty — cognate with heave. Used as a color modifier since at least the seventeenth century to indicate weight in saturation as much as value: heavy with pigment, heavy-bodied. In the engine's adjective grid, heavy sits alongside deep and plush in the dark-and-saturated quadrant. Closer to a fabric description than a pure value word.

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.

The dense canopy of a temperate or tropical woodland — oak, beech, pine, eucalyptus, mahogany — wherever leaves close above to filter the light below. Forest green refers to the average reflectance of a healthy mid-summer canopy seen from below: a saturated, slightly muted green with the matte finish of layered chlorophyll. Deeper than fern, cooler than olive, with the ecological weight of a word that has named every wooded biome on Earth.