Semantic Extension and Grammaticalization of SAME in Korean Sign Language (KSL) and Korean

Semantic extension and grammaticalization have been extensively studied in spoken languages, but sign languages remain relatively underrepresented. This paper investigates the semantic extension and grammaticalization of the lexeme [SAME] in Korean Sign Language (KSL) and compares them with the spoken Korean counterpart kath-‘be same’. The investigation yields both commonalities and differences in the developmental paths of these two lexemes. Parallels are found particularly in their progression from the original meaning of IDENTICALNESS to the more abstract meaning of CORRECTNESS, and further to epistemic-evidential functions, such as INFERENTIAL CONJECTURE, and the pragmatic-interactional function of MITIGATION. While both [SAME] in KSL and kath-in Korean undergo grammaticalization, their trajectories are partly shaped by modality-specific constraints. The spoken modality allows kath-to evolve toward similarity, whereas the visual-spatial modality of KSL, constrained by iconic distinctions, prevents [SAME] from extending into the domain of similarity, as this function is already occupied by the iconically related sign [SIMILAR]. While previous studies on modality-specific grammaticalization in sign languages have focused primarily on the process of gestures evolving into lexical items, the present study opens up the possibility that additional modality-specific factors may influence the pathways of grammaticalization as well as lexical semantic extension in sign languages.