Greek and Latin have developed from their common Proto-Indo-European (PIE) ancestor in distinct ways, resulting in two languages that exhibit very different features, in particular regarding phonology and Wortbildung. Moreover, the Greek lexicon has long been recognised for its huge proportion of non-inherited words, among which it is difficult to draw a clear distinction between substrata and loan words. Several of the languages that contributed to shaping the Greek lexicon are Indo-European. Among the Indo-European contributors to the non-inherited Greek lexicon, we tentatively identify a language that shares phonetic and morphological features with substratic elements attested in Italic, and possibly articulatory properties of Latin itself. We shall review five phonetic features of this language: (i) voiceless reflexes of PIE voiced aspirated stops; (ii) the anticipation of nasals resembling lex-unda in Latin but generalised to labial stops, such that VCnV > VnGV with lenition of the consonant; (iii) a velarised /ł/ (viz. l pinguis) which can trigger an anaptyctic -ŏ- or -ŭ-; (iv) apparent voice alternations that follow similar patterns to the Verner law in Germanic; (v) the metathesis of -r-, such that CVrC > CrVC. Our study also unveils morphological peculiarities of this language: (a) the frequent use of elsewhere poorly attested labial morphs, leading to nouns of the form *CóC-Po- and adjectives of the form *CoC-Pó-; (b) the frequent use of a prefix *eǵhs- (cf. Lat. ex-, Gr. ἐξ-) reflected as a simple *s-; (c) the frequent occurrence of action nouns built with the well-known *CóC-no- pattern.