Origins
The English word 'yellow' belongs to one of the most prolific and far-reaching etymological families among colour terms. It descends from Old English 'geolu,' from Proto-Germanic *gelwaz, from the PIE root *gʰelh₃- meaning 'to shine, to gleam,' with secondary colour senses of 'yellow, green, bright.' The sheer number of English words descended from or related to this root is extraordinary: gold, glow, gleam, glint, glitter, glass, glaze, gloss, glad, gall, and yolk all trace back to this single PIE ancestor.
The development from *gʰelh₃- to the Germanic colour word follows a common pattern: an original verb meaning 'to shine' produced an adjective meaning 'shining, bright,' which then narrowed to a specific colour. Proto-Germanic *gelwaz meant specifically 'yellow,' as do its regular reflexes in the daughter languages: German 'gelb,' Dutch 'geel,' Swedish 'gul,' Danish 'gul,' Norwegian 'gul,' and Icelandic 'gulur.'
Outside Germanic, the PIE root *gʰelh₃- produced an equally impressive set of descendants. Greek 'khlōrós' (pale green, yellow-green) is the source of English 'chlorine' (named for the greenish-yellow colour of the gas), 'chlorophyll' (literally 'green-leaf'), and 'chloroplast.' Latin 'helvus' meant 'honey-yellow' or 'dun.' Lithuanian 'žéltas' means 'yellow.' Old Church Slavonic 'zelenyĭ' means 'green,' showing how the root vacillated between yellow and green in different branches — a pattern consistent with the root's original meaning of general brightness rather than a specific hue.
Proto-Indo-European Roots
The relationship between 'yellow' and 'gold' deserves particular attention. 'Gold' descends from Old English 'gold,' from Proto-Germanic *gulþą, from PIE *gʰl̥h₃-to- — a derivative of the same root *gʰelh₃-. Gold was named for its colour, which was named for its shininess. The word 'yolk' (the yellow part of an egg) comes from Old English 'geolca,' a diminutive of 'geolu' (yellow) — literally 'the little yellow thing.'
The connection to 'gall' (bile) is equally revealing. Old English 'gealla' (gall, bile) descends from the same PIE root, because bile is yellowish-green in colour. This gave rise to the metaphorical sense of 'gall' as bitterness or impudence. The medical term 'jaundice' comes from Old French 'jaunisse' (yellowness), from 'jaune' (yellow), from Latin 'galbinus' — yet another descendant of the same PIE root.
The phonological development from Old English 'geolu' to Modern English 'yellow' involves the palatalization of initial /g/ to /j/ before front vowels, a regular Old English sound change (the same process that gave 'year' from Old English 'gēar' and 'yield' from 'gieldan'). The Old English 'geo-' became Middle English 'ye-,' and the inflectional ending '-u' evolved into '-low' through the vocalization of the labial consonant /w/ in the stem.
Later History
Semantically, 'yellow' has accumulated both positive and negative connotations. The positive associations — sunshine, warmth, cheerfulness, gold — are ancient. The negative ones are more culturally specific. 'Yellow' as a synonym for cowardly ('yellow-bellied,' 'yellow streak') is attested from the nineteenth century in American English, though its precise origin is debated. 'Yellow journalism' dates from the 1890s, named after the Yellow Kid comic strip published in rival New York newspapers owned by Pulitzer and Hearst.
In East Asian cultures, yellow has carried imperial and sacred associations quite different from Western usage. In China, yellow was historically the emperor's colour, and the 'Yellow Emperor' (Huangdi) is a legendary founder of Chinese civilization. These cultural associations are independent of the word's etymology but illustrate how differently the same colour can be valued across civilizations.
In the Berlin and Kay colour-term hierarchy, yellow typically appears at stage III or IV, making it one of the earliest colours named after black, white, and red. This early emergence across unrelated language families reflects yellow's high luminance and distinctiveness in natural environments — the colour of sunlight, fire, and many edible fruits.