Binomial adjective doublets in Japanese: A Relational Morphology account

Adjectives whose stems consist of two elements (or binomial adjectives) are becoming increasingly productive in colloquial Japanese. Unlike the stems of conventional adjectives, the stems of numerous, but not all, innovative binomial adjectives can have two distinct inflectional behaviors (e.g., daru-omo-{i / na} ‘be languid and heavy’, aza-kawai-i / aza-kawa-na ‘be shrewd and cute’) and have different syntactic properties depending on the suffix. Within the framework of Relational Morphology, the current study proposes that two independently established word-formation rules, represented as “sister schemas,” account for the apparent derivational gaps in these adjectives and their difference in productivity. I -forms are crucially based on particular subschemas, such as X- kawai-i ‘be X and cute’ and kuso -Y- i ‘be very Y’, and are not fully productive, whereas na -forms have detailed morphophonological constraints and are notably productive. The two suffixes are available only if an adjective stem meets the structural and semantic requirements of both schemas.