Here's an idea I've been toying around with for a bit: The Kosi language has only five colours, equivalent to English 'white', 'black', 'red', 'blue', and 'green'. The lack of other colours could be explained by some sort of defect in the eyes. (The colours wouldn't even be independent lexical items: the word for 'red', for example, would be a compound meaning something like 'blood-coloured', a feature which IIRC Pirahã has). Is this system plausible? (I know next to nothing about such things...) Trebor Support the fight against the lack of choice on November 2: spoil your ballot!