Students can have fun seeing how the dictionary tries to define colours: Chambers gives blue as ‘the colour of the unclouded sky’, and yellow as ‘the colour of sulphur, egg yolk, gold, a ripe lemon, a primrose, etc.’ The 1944 edition of the Concise Oxford Dictionary mentions buttercups.
Interesting also are the connotations of some colours: yellow, blue, green, scarlet, etc., some of which have passed in and out of fashion. For example, the boy Leo in The Go-Between is taunted for being green, and Charles Pooter in The Diary of a Nobody is asked if he has an estate in Greenland. This was popular usage.
The suggestion is sometimes made that Latin is poorly furnished with names for colours, and of course it does not have anything like the number of English words, so many of which are imports over the ages. But it has a selection:
candidus glowing white
ferrugineus dark red, rusty
roseus, ruber, russus, rufus shades of red
coccinus, miniatulus, puniceus scarlet
rutilus red inclining towards golden
fulvus deep yellow, tawny, (eg of lions)
croceus saffron coloured, orange-red
flavus golden yellow, reddish yellow, flaxen coloured
luteus golden yellow, the colour of an egg yolk
luridus, gilvus shades of pale yellow
ravus greyish yellow
prasinus leek green
pullus dark grey
spadix dark brown, chestnut brown
Then there comes the group of words—purpureus, phoeniceus, blatteus, conchyliatus, ostrinus—usually translated as purple, and here translation fails. These words are often used with the connotation of riches or royalty, and purple has that connotation in English also.
But purple in modern English denotes a colour closer to mauve or violet (it is interesting to bring up these two words in Google Images), whereas the above words in Latin denote something more like what we would call crimson (a word that originates in Arabic).
The 2006 edition of Chambers is straightforward about it:
purple… a mixture of blue and red; crimson(hist); the Tyrian crimson dye, obtained in ancient times from various shellfish (Murex, Purpura, Buccinum, etc)
Next post: The Purple Chamber, and more about colours.