Casper

#aab5b8

A neutral that has no useful hue — it reads as a grey. It is light — black text sits on it comfortably, white text does not.

Hex

#aab5b8

RGB

170, 181, 184

OKLCh

76.5% 0.013 215.8°

CIELAB (D50)

72.9, -3.5, -2.9

What is true of this colour, and of no other

15 other named colours sit within ΔE00 2 of it — this part of the space is crowded, and the names here are finer distinctions than most people make.
It uses only 10% of the chroma available at this lightness and hue — there is a far more vivid version of this colour inside sRGB.
As text on white it measures APCA Lc 41.1; on black, Lc -61.2. The sign is the polarity, which the WCAG ratio discards.
Built into an eleven-step scale, 10 of the 10 adjacent pairs stay ΔE00 2 apart — see the ramp.
protanopia and deuteranopia and tritanopia shift it by ΔE00 5.6 and 6.0 and 14.5 — no red cone.

Text on this colour

White text

2.10:1 — fails AA

Black text

10.01:1 — passes AA

Black text is the better of the two at10.01:1. That is enough for body text.

As text on white, it needs to change

#6e797b is the nearest colour of the same hue that passes AA on white, at 4.50:1. Only the lightness moved.

Try it against your own background

The same colour, with one cone missing

As you see it

#aab5b8

protanopia

#b4b4b8 · ΔE00 5.6

deuteranopia

#b2b2b8 · ΔE00 6.0

tritanopia

#b0b0d4 · ΔE00 14.5

Run a whole palette through all three

The twelve nearest named colours

Ranked by CIEDE2000 — perceptual distance, not hex arithmetic. The closest isNautical Star at ΔE00 0.505: below 1.0 — an ordinary observer cannot tell these apart, even side by side. What the numbers mean.

Nautical StarΔE00 0.505 · #aab5b7
Yreka!ΔE00 0.831 · #a7b3b7
Winter Morning MistΔE00 0.969 · #a7b3b5
Smoke CloudΔE00 0.972 · #adb6b9
StardewΔE00 0.996 · #a6b2b5
Lake PlacidΔE00 1.092 · #aeb9bc
Autumn FogΔE00 1.305 · #afb8ba
Special DeliveryΔE00 1.462 · #a5b2b7
Shaved IceΔE00 1.494 · #a9b4ba
Half Sea FogΔE00 1.752 · #a9b8bb
Blue ArrowΔE00 1.791 · #a9b7b8
Mirror MirrorΔE00 1.801 · #a8b0b2

12 of these have no page of their own: pages exist for the 4,961 colours the dataset marks as good names.