The word ptyx is used by Mallarmé in a poem published in 1887. In order to establish its meaning, one needs to investigate closely the Saussurian distinction between signified (signifié) and thing signified (chose signifiée). As for the material form of the word, it is derived from the Boppian version of Indo-European linguistics. Mallarmé was familiar with it, as it appears in Les Mots anglais. The paper tries to show that the sequence /ptyks/ makes it possible to produce, by combining various permutations and modifications, all possible consonantal forms of all possible Indo-European words. Thus the ptyx is The Word as such, except that it is lacking the Boppian fundamental vowel /a/. It is this /a/ that the poet will seek to find near the Styx. From that starting point, it becomes possible to explain the poetic function of the ptyx and the whole poem itself; in these matters, the Saussurian anagrammatic hypothesis will appear to be most fruitful.