This article contributes to the study of the grammar, semantics, expressive values of a very special onymic category, inhabitants’ names, or demonyms. The authors examine and compare demonyms in two varieties of Romanic languages — South American Spanish and Brazilian Portuguese from both a multi-modal point of view and empirical evidence (synchronic and diachronic data) and systemize them by concentrating on their morphosyntactic distinctive features and semiotic content. The perspective revealed in this paper aims to study, define and analyze the main tendencies in the creation of denominative adjectives functioning as demonyms, to establish the parameters of discrepancies and convergences regarding demonyms of the region in question. The authors based on analyzing the motivation sources, grammar formulae, suffix combinations, socio-cultural varieties and the occurrence of homonymy, as well as their significance, axiological values in forming a group identity and the stereotypes they might lead to. The methodology has included semiotic, cognitive, historic and comparative analysis — a synchronic conceptual transdisciplinary analysis. The results of the study confirm the premise that the demonym suffixes randomly alternate in derivation processes, but also demonstrate the existence of other morphological and pragmatic trends while outlining the role of demonyms in migration processes, formation of a linguistic landscape and axiological values. © Chesnokova O.S., Radović Marija, Kotenyatkina I.B., 2021.