A color English already had, then borrowed again
In modern English, blue is the everyday name for the hue of a clear sky, of many dyes and flags, and of a bruise. As a noun it can mean the color itself, the sky, or the open sea. Those uses feel as old as the language. They are not. The origin of the word blue is a medieval borrowing that displaced native English color terms of the same family.
French forms in Middle English
The adjective is first recorded around 1300, in Middle English spellings such as bleu, blew, blwe, and bloo. It came from Anglo-Norman and Old French, where bleu — also blo and a crowd of related spellings — already meant more than one shade. In the early twelfth century the French word could describe a pale, wan, or livid face, a leaden or bruised look, even blond hair. By about 1150 it also named the color of a clear sky. English took in that spread of senses, not a single paint-box chip.
French did not invent the stem. The usual account traces it to a Germanic source, reconstructed as Frankish *blāo or a close cousin, the same stock that later gives German blau, Dutch blauw, and the Scandinavian forms written blå. Some descriptions allow a late Latin stepping-stone: Isidore of Seville records forms such as blavus. Even if that intermediary is real, the French color term is Germanic underneath, not a descendant of classical Latin caeruleus or the older native Latin color vocabulary.
The spelling that English now treats as standard is later. Blue appears in the sixteenth century and becomes the ordinary written form only around 1700, still under French pressure. Older English texts keep blew and blewe long after the spoken word had settled.
The root behind the borrowing
The Germanic ancestor is reconstructed as Proto-Germanic *blēwaz or *blæwaz, a word for blue or dark blue. Behind that sits an Indo-European base often given as *bʰlēw- or *bhle-was, a label for light or bright color rather than for one modern hue. That base is usually linked to the shining root *bhel-, which also feeds words for flash, burn, and pale brightness.
The same layer explains why the English color name has cousins that do not mean blue at all. Latin flavus is yellow. Welsh blawr is gray. Middle Irish blá could mean yellow. Early Indo-European color words often slid among yellow, gray, pale, and what later languages split into blue. Inside Germanic the match is no neater. In Middle High German, bla could cover yellow as well as blue. Older Scandinavian uses of related words could point to a dark, livid, even swarthy tone, not a bright midday sky. Color terms in this family named a region of light and darkness, not a wavelength.
English already possessed direct descendants of that Germanic adjective. Old English had blāw, along with bluish formations such as blǣwen and compounds that mixed the root with hǣwen. Dialectal later English blow, meaning blue, is a native doublet rather than a second borrowing. Those forms prove the root was at home in English before the French word arrived.
Why the native words did not win
Old English did not, however, treat blāw as its ordinary everyday name for the hue. The more common native term appears to have been hǣwen, a blue-gray word related to the family of hoar. After the Old English period, neither hǣwen nor blāw remained the usual color name. The French borrowing took the job.
That replacement is one of the clearer facts in the history, and one of the odder. A Germanic language already had a Germanic color word of this stock, then adopted a French look-alike of the same stock after the Conquest. Why the native terms faded is not fully settled. One line of research, associated with C. P. Biggam, ties the shake-up in early English color vocabulary to the political and linguistic upheaval of the Norman period. The claim is not that speakers forgot the sky; it is that the preferred label for it changed under contact.
A further uncertainty sits on the French side. Anglo-Norman and Old French also had bloi, a word for fair, golden, light, or blond, and in some records for blue. It may be a separate item, perhaps with a Celtic source, that later mixed with bleu in spelling and sense. If that merger happened, some of the paler and yellower French meanings may not belong to the Germanic blue word at all. Dictionaries mark the point as possible, not proven.
Bruises, loyalty, and later loads
The livid, lead-colored sense never dropped out. It is the one in black and blue, and it may have been reinforced by the Old Norse cognate blár, which could mean leaden as well as blue. Blue in the face, recorded in the nineteenth century after an earlier black and blue in the face, still pictures a congested, bruised complexion rather than a fashion shade.
From at least Chaucer’s time the color could also stand for constancy. Later English packed that emblem into true blue. The link is conventional: loyalty was painted this color because verse, cloth, and custom said so, not because the sky looks faithful.
A figurative sense “sad, downcast” is attested from about 1400. A common explanation ties it to the bruised meanings — low spirits colored like a hurt body — though that remains a plausible reading rather than a demonstrated path. Still later, the adjective picked up other loads that sit on top of the color word: learned or pedantic when applied to women in the bluestocking period of the late eighteenth century; lewd or indecent from the mid-nineteenth century, by a route that remains unclear. Those senses matter for later English, but they do not explain how the color name entered the language.
As a noun, the word tracks the adjective. It names the color from the same Middle English period, blue clothing from the late fifteenth century, the sky from the seventeenth, and the sea from the early nineteenth. Political parties that chose the color as a badge, and trades that wore blue livery, added still more specialized uses without changing the underlying etymology.
A cousin English let go
The durable fact is the near miss. German kept blau, Dutch blauw, Icelandic blár. English had blāw and let a Norman form of the same root replace it, then spent centuries settling the spelling on blue. The hue of the sky did not need importing. The standard English name for it did.