Origins
The English word 'blue' has a more circuitous history than most basic colour terms, having entered the language not through direct Germanic inheritance but through a French detour that loops back to Germanic origins. Modern English 'blue' derives from Middle English 'bleu' or 'blew,' borrowed from Old French 'bleu' in the thirteenth century. The Old French word itself came from Frankish *blāo, the language of the Germanic Franks who conquered Gaul, which descended from Proto-Germanic *blēwaz. So 'blue' is a Germanic word that left home, passed through French, and returned to a Germanic language in Norman dress.
Old English did have its own native descendant of *blēwaz: the word 'blǣwen,' meaning blue or livid. But this native form did not survive the massive French lexical influence that followed the Norman Conquest of 1066. By the thirteenth century, the French-derived 'bleu' had almost entirely displaced 'blǣwen' in English usage.
The Proto-Germanic root *blēwaz traces further back to the PIE root *bʰlēw-, and here the story takes a surprising turn. This root did not mean 'blue' exclusively — it encompassed a range of light colours including blue, blond, and yellow. Latin 'flavus' (golden-yellow, blond), which gave English 'flavescent,' descends from the same PIE root. The idea that blue and yellow could share a root seems paradoxical to modern speakers, but PIE colour vocabulary was organized differently from modern systems, often grouping colours by luminosity or saturation rather than hue.
French Influence
This ancient ambiguity between blue and yellow echoes in other Indo-European languages. Old Norse 'blár' could mean blue, dark blue, or even black. The Germanic root also appears in 'blond' (via Old French, ultimately from a Germanic source meaning 'yellow' or 'fair'), reinforcing the light-colour association of the original root.
The cultural and linguistic history of blue is remarkable for its lateness. Many ancient languages lacked a distinct term for blue. Homeric Greek used 'kyaneos' (dark, shadowy) and 'glaukos' (light, gleaming) for what modern speakers would call blue, but neither word mapped neatly onto the modern colour category. Homer's famous 'wine-dark sea' (oinops pontos) has puzzled scholars for centuries — the epithet seems to describe the sea's darkness and shimmer rather than its hue. Biblical Hebrew similarly had no dedicated blue word; 'tekhelet,' sometimes translated as blue, referred specifically to a costly dye rather than to the colour category itself.
William Gladstone, the Victorian prime minister and classical scholar, first noted the apparent absence of blue in Homer in 1858, sparking a debate that continues today. Lazarus Geiger observed in the 1870s that blue terms appear later than red, yellow, and green in the linguistic development of nearly all languages. Berlin and Kay's 1969 framework confirmed this: blue typically enters a language's basic colour vocabulary at stage V or later, after black, white, red, yellow, and green.
Figurative Development
In English, 'blue' has developed an exceptionally rich metaphorical life. Sadness ('feeling blue') may derive from a nautical custom of flying blue flags when a ship's captain died, or from the association of blue with cold and melancholy dating to the sixteenth century. 'Blueprint' originally referred to the cyanotype photographic process used for architectural plans. 'Blue blood' translates Spanish 'sangre azul,' which Castilian aristocrats claimed because their pale, unexposed skin showed blue veins — a marker of not having Moorish ancestry. 'Bluestocking' for an intellectual woman traces to the informal literary gatherings in 1750s London where the botanist Benjamin Stillingfleet attended in everyday blue worsted stockings rather than formal black silk.
The phonological development of the word is straightforward: Old French 'bleu' entered Middle English with essentially its modern pronunciation /bluː/, and the spelling has been stable since the sixteenth century, though earlier spellings included 'blew,' 'blewe,' and 'bloo.'