For the same reason that you have the preceding genitive nan neòil (I suppose the standard/traditional genitive would be nan neul but don't know what else it could be here). A' seòladh nan neòil [agu]s [a' seòladh] an domhain liath. "Sailing the clouds and [sailing] the grey-blue universe." It doesn't matter that the verbal noun seòladh isn't expressly used in the second line, it still affects the following noun domhan.poor_mouse wrote:I thought that 'an domhain' might be singular, but in this case it would be genitive and why genitive here?
On the other hand, it may be 'an'='their', but it also hasn't much sense, has it?
We had an interesting debate about this about a year ago, starting here:conmaol wrote:To confuse things further, "liath" can mean either "blue" or "grey".
http://www.foramnagaidhlig.net/foram/vi ... 424#p12424
With some simplification what happened was that Gaelic "divided the pallette of colours" with borderlines sometimes elsewhere than in other languages, so that from its viewpoint for instance liath is a continuum of one colour ranging from light grey to light blue, but darker grey is covered by glas and darker blue by gorm. Some others disagree with me but I believe that whether you link light grey to light blue or to dark grey is a purely artificial matter. That is to say, unless you use some scientific method like making the borders according to the percentages of the basic CMYK or RGB colours in a specific hue - but surely such methods played no role when these terms for colours were being coined.