Entombed Senex Cobalt
Entombed Senex Cobalt (#253D7F) is a deep azure with an earthy character. It leans grounded and natural, the kind of color that plays well with wood, clay, linen, and warm neutrals. Its HSL profile (224°, 55%, 32%) places it in the balanced band at a dark lightness. It works well as a headline, icon, or deep background in an otherwise light layout, pairing cleanly with cream, bone, and warm neutrals. For a confident two-color system, pair it with its complementary amber. For something softer, pull in its analogous neighbors on either side of the wheel.
Etymology
Old French en-tombe, into-the-tomb — past-participle of entomb. As a color modifier, entombed implies the deep, sealed, untouched-by-light darkness of a sepulchre interior of medieval-and-Renaissance European cathedral architecture. Sits at the deep-and-funereal end of the grid, parallel to sepulchral and crypted in usage.
Latin senex, old-man-or-elder. As a color modifier, senex implies a Latin-elder-and-Roman-Senate-elder quality, the visual register of Cicero-Cato-the-Elder-senex hand-Latin-elder-and-Roman-Senate-elder Cicero-Cato-the-Elder-senex-and-De-Senectute senex-and-Latin-elder-and-Roman-Senate-elder surfaces under Cicero-Cato-the-Elder-senex-and-De-Senectute Roman-Senate-and-villa-retreat venerable-elder-light. Sits at the modifier-and-Latin end of the grid, parallel to pater and virtus in usage.
Element Co, atomic number 27 — German Kobold, goblin, named by miners who found the metal interfered with smelting silver ore. Cobalt blue is the cobalt-aluminate pigment introduced by Louis Jacques Thénard in 1802: a saturated, slightly green-shifted deep blue with the matte finish of mineral pigment in oil. Cooler than ultramarine, warmer than prussian, with the painter's weight of a pigment used by Renoir, Van Gogh, and Cézanne.
Closest matches
The nearest named color in three reference sources, ranked by perceptual distance (ΔE76 in CIELAB). ΔE < 1 is imperceptible to most viewers; ΔE > 10 is clearly different. When two sources point to the same hex they’re merged into one tile; click any to open that color’s page.
Variations
Click any swatch to exploreHarmonies
Accessibility
How this color appears to viewers with the four major color-vision-deficiency types. Computed via the Machado (2009) physiologically-based model. If a tile matches the original, the color reads the same to that viewer.
The color used as foreground text against pure white and pure black, with the contrast ratio and WCAG 2.1 grade. Aim for AA (4.5:1) for body text and AA Large (3:1) for 18 pt+ headlines; AAA (7:1) is the gold standard for long-form reading surfaces.
Wide gamut
The CSS Color 4 wide-gamut form of this color. Both swatches render the same color on every display — the P3 form only diverges from sRGB when a designer pushes channels outside sRGB's reach.
Moderately saturated colors gain a small bump in P3 — the difference is usually visible side-by-side on wide-gamut hardware but won't change the character of the color.