The etymology of Greek βαθύς ‘deep’ has generally been considered obscure, in particular when its form and meaning have been hypotetically connected to other similar Greek words, such as βάθος, βόθρος/βόθυνος, βῆσσα/βᾶσσα, βέθος, βυθός/βυσσός/ἅβυσσς etc. In the present discussion a new etymological interpretation is proposed according to two concurring hypothesis. The former one assumes that Grassmann’s Law could have already operated earlier then the desonorization of the i.e. voiced aspirated stops into the voiceless ones. The latter one – thanks to the assumptions of cognitivism and prototypical fuzzyness – interprets βαθύς as a part of a semantic group which contains couples formed by an adjective in -ύς (characterized by radical vocalism in -α-) and a neuter substantive in -ος, connected on the basis of the idea of ‘dimension’. An analogical mechanism could have triggered starting from the semantic continuum mentioned above. Due to such an etymological interpretation, indeed, most of the Greek words denoting ‘depth’ are led back to the same i.e. root *bhedh ‘to dig, to prick’.