Plain Creep Robin

Latin planus, flat, level — used as a color modifier since the medieval period for hues that read as undecorated and direct. Plain white, plain blue: moderate saturation, no shift, no surface effect. Sits in the crisp-bucket center, with the implication of restraint rather than absence.

Old English crēopan, to-move-slowly. As a color modifier, creep implies a slow-stealthy-and-spreading quality, the visual register of ivy-on-wall-and-mist-creep hand-slow-stealthy-and-spreading ivy-on-wall-and-mist-creep-and-spreading-shadow crept-and-slow-stealthy-and-spreading surfaces under ivy-on-wall-and-mist-creep-and-spreading-shadow ruined-cloister-and-river-valley-and-evening-meadow encroaching-light. Sits at the modifier-and-mood end of the grid, parallel to lurk and prowl in usage.

The American robin (Turdus migratorius) — though the color refers not to the bird's red breast but to the egg, robin's-egg blue, a pale slightly green-shifted blue produced by biliverdin pigment in the eggshell. The color is the inside surface of a fresh robin's nest at peak laying: a soft, slightly green-shifted pale blue with the matte finish of avian eggshell. Lighter than aqua, cooler than turquoise.