The Latin ‘third stem’ and its Romance descendants

The ‘third stem’ in the Latin verb provides one of Aronoff’s best-known illustrations of the notion of ‘morphome’: unpredictably variable in form, it is also consistently associated with an abstract and heterogeneous pattern of distribution. My perspective is diachronic, exploring the history of the third stem as it continues into Romance (especially Romanian). My findings support the ‘psychological reality’ of the morphome for successive generations of speakers, but suggest also that unity of lexical meaning is of central importance in the diachronic persistence of morphomes in general, such persistence finding an explanation, perhaps surprisingly, in universal principles of form-meaning iconicity.