Dick, in my view it is possible for someone to wear two hats and be be both a traditional singer and a jazz singer. However your latest example is rather different from what we have previously been discussing, which was singers who included songs from other genres and sources alongside those they had acquired from within the tradition.

Besides, "traditional singer" in the context we are discussing it is not a hard-and-fast term but is specialist usage among a specific interest group. We have already seen examples earlier in the thread of how "traditional" means different things in different genres. If there were a traditional singer who also sang songs in a jazz style, then so far as the folk community is concerned he would probably still be regarded as a traditional singer, because that is the aspect which is important to that interest group. The jazz community might view him as a jazz singer who also sings folk songs.

It's a matter of perspective, but as this is a folk music forum that is the perspective we should be viewing it from. From that perspective, whilst it may be perfectly valid to label a singer according to their repertoire, to me it is not helpful. If they can be a traditional singer one minute, a jazz singer the next, or a C&W singer after that, all that does is tell what that singer is singing at a particular point in time. What it does not do is make what is (to me at least) an important distinction between someone who sing sings traditional songs and other songs from within the tradition, and someone like me who came to those songs from outside it.