Suffixal derivation in 18th century terminology: a study on the suffixes os(o) and -ad(o) in Vandelli’s work

Abstract

This paper investigates suffixal derivation in eighteenth-century Portuguese scientific terminology, focusing on adjectives formed with the suffixes -ad(o) and -os(o) in the Diccionario dos Termos Technicos de Historia Natural (1788), by Domingos Vandelli. The main objective is to understand the mechanisms of lexical enrichment involved in the formation and consolidation of Portuguese as a scientific language at a historical moment marked by the transition from Latin to vernacular languages as vehicles of scientific knowledge. The study adopts a combined morphological and etymological approach, articulating structural analysis with historical interpretation, and is grounded in the concept of neologism proposed by Alves (2007). Terms are considered neological when no attestation prior to 1788 is recorded in the Dicionário Houaiss Online. The analysis of the corpus identified 14 neological adjectives formed with -ad(o) and 13 with -os(o) . Most of these terms present direct Latin correspondents, frequently attested in Vandelli’s own dictionary (e.g. ciliatus, bulbosus, tuberculatus), which highlights the central role of Latin as a model for scientific lexical formation. These data indicate that such units cannot be explained solely as endogenous formations of Portuguese, but rather as adapted Latinisms, that is, lexical items whose etymon is Latin while their morphological structure conforms to Portuguese derivational patterns. Regarding the suffix -ad(o), the results show that it cannot be reduced to the function of a verbal past participle ending. Instead, it operates productively as a denominal adjectival suffix, including in cases where no corresponding verb is attested in Portuguese. The suffix -os(o), in turn, displays a more stable derivational behavior, regularly forming adjectives from nouns and, in several instances, recovering erudite bases of Latin origin. In both sets of data, the analysis demonstrates the importance of clearly distinguishing between morphological structure and etymological description: although these terms are morphologically analyzable as suffixal derivatives in Portuguese, their historical formation involves processes of calquing from Latin. The study concludes that Vandelli’s work played a crucial role in the diffusion and systematization of scientific terminology in Portuguese, significantly contributing to the establishment of the language as a medium for scientific discourse. Furthermore, the diachronic analysis of the suffixes -ad(o) and -os(o) reveals how eighteenth-century lexical practices helped shape derivational patterns that remain productive in contemporary Portuguese, thereby enhancing our understanding of the historical development of scientific and technical vocabulary and of Portuguese derivational morphology.