Antiseptic Alcove Sky

Greek anti- (against) plus sēptikós (putrefying) — adjectival suffix -ic. As a color modifier, antiseptic implies a clear-and-disinfected-and-clinical quality, the crisp color of medical-laboratory and operating-theater hand-scrub-and-sanitizer surfaces. Sits at the crisp-and-clean end of the grid, parallel to sterile and sanitary in usage.

Arabic al-qubba, the-vault. As a color modifier, alcove implies a recessed-bedroom-or-sitting-area quality, the visual register of English-and-French-Country-House-alcove hand-built recessed-and-vaulted bedroom-or-sitting-area-recess-and-window-seat architectural surfaces under English-and-French-Country-House alcove-recess light. Sits at the modifier-and-architecture end of the grid, parallel to niche and atrium in usage.

The blue of a clear sky at noon — produced by Rayleigh scattering, the preferential dispersion of shorter wavelengths through atmospheric molecules. Air itself is colorless; the color we see is sunlight scattered toward our eyes by every cubic kilometer above. The reference shade is mid-latitude noon under a high pressure system: a clean, slightly green-shifted blue with the luminous depth of light scattered across an entire hemisphere of air.