Old English geol(o)ca, from geolu 'yellow'.

• yellow from Old English:

  As with other colour words such as auburn and brown, the root of yellow probably referred to a wider range of colours than the modern word. It shares an ancestor with gold (see golden), but is also related to gall (Old English), bile (mid 17th century), and the final element of melancholy, all of which derive from the greenish colour of bile. The yellow egg yolk (Old English), which could be spelt yelk into the 17th century, was also related to yellow. In the 17th century yellow rather than green was the colour of jealousy, possibly with the idea of a jealous person being ‘jaundiced’ or bitter. The word jaundice (Middle English) is from Old French jaune ‘yellow’, from the symptomatic yellowish complexion. Yellow is now associated with cowardice, a link that began in the 1850s in the USA. Since the 1920s a coward has been said to be yellow-bellied or a yellow-belly.