The term ‘Sigmatic’ reflects - somewhat imprecisely - mathematical symbol Σ, which indicates the sum of a number of terms - in this case a number of languages. It is here taken to refer to what is argued to be the common ancestor of Semitic, Berber and Egyptian, an agglutinating language which is also argued, albeit tentatively, to bear a degree of structural relationship to Sumerian.
That there are also relationships of various kinds between Sigmatic and the relevant African languages is not denied, but these relationships are argued to be considerably more elusive and more complex than the all too simplistic links so often proposed by Afroasiaticists.
1. On the Biradical Origins of the Semitic Triradical Root System