Our project

The research project The lexicalization of the adjective class in Indo-European and Semitic (MUR code: 2022WHZJ98) bridges historical and typological linguistics. Its main contributions relate to parts-of-speech (PoS) typology, Indo-European (IE) and Semitic studies, as well as linguistic terminology, theoretical morphology, and the history of language sciences. 

It is well known that no universally accepted and internally consistent theory of PoS classification has been proposed to date. Moreover, some scholars believe not only that such a theory is currently lacking, but that it is, in principle, impossible. This project challenges that view by offering two main contributions: 

i) it proposes a new and coherent theory of PoS classification applicable across languages, tested against a balanced sample of 60 languages; 

ii) it applies this theory to analyze two major, yet previously neglected or understudied, typological shifts in PoS that occurred in two of the world’s most ancient language families—Indo-European and Semitic. 

These language families were chosen for their long and uninterrupted textual traditions, which enable the reconstruction of long-term typological developments. Moreover, both families exemplify a previously undescribed type of change. Adapting the concept of grammaticalization, we term this new type of shift lexicalization: the emergence of a primary class of adjectival morphemes within the lexicon of a language. More specifically, it refers to the shift of a “major” PoS from the domain of constructions (i.e., grammar, and in particular word-formation) to that of the lexicon. In both language families under investigation, it is the adjective class that undergoes this lexicalization process. 

Identifying this change not only advances our understanding of typological linguistics but also enables us to propose a cross-linguistically valid, functional definition of the most important (and discussed) unit in historical linguistics: the root. Until now, no one has established a connection between the concept of root and PoS typology. Most scholars reject such a link, viewing the root either as a purely diachronic or formal notion (e.g., a consonantal template), or as simply a verb stem labeled differently in tribute to early Indian or Arabic grammarians (e.g., Skt. dhātu- ‘base, foundation’, Ar. ’aṣl or mādda ’aṣliyya ‘root, trunk’, Heb. šoreš ‘id.’). 

This project argues against that view by demonstrating that the Sanskrit and Arabic root is neither merely formal nor exclusively diachronic. Rather, it is the lexical morpheme in a system where only two major classes of morphemes exist: verbal roots and nouns. In such systems, adjectives typically emerge as derived stems—nominalizations—formed from verbs denoting qualities, aligning with what Dixon terms verb-like adjectives.