Abstract
Aims and objectives: This study investigates a recent grammatical innovation in Western Basque: the emergence of a conditional grammatical gender agreement (GGA) system. While Basque is traditionally classified as morphologically genderless, this research examines how intense, long-term contact with Spanish has led to adjectival gender distinctions, shifting the language toward a new typological category.Methodology: The research utilizes a triangulated mixed-methods approach, combining a sentence completion task and a matched-guise test. Data were collected from 20 young adult traditional speakers (euskaldun zaharrak) in Mundaka (Bizkaia) and compared with data from the proximate community of Ondarroa to assess the impact of contact intensity on structural change.Data and analysis: Results demonstrate categorical use of feminine morphology (-ie) with female referents in Mundaka. Crucially, agreement extends beyond Spanish loanwords to native Basque-origin stems (e.g., gizajo/a, potolo/a), representing structural borrowing of inflectional morphology. Attitudinal data reveal that feminine morphology is perceived as significantly more natural and respectful than the masculine form for female referents, regardless of etymological origin.Conclusions: The findings confirm a 'conditional' GGA system that is lexically restricted but structurally entrenched. The contrast between rigid consensus in Mundaka and higher variability in Ondarroa suggests that borrowed features are mediated by local sociolinguistic pressure. This innovation represents 'identity policing', where speakers utilize borrowed categories to protect linguistic boundaries.Originality: This research provides the first systematic empirical evidence of Spanish-style gender agreement transferred onto native Basque inflectional morphology, refuting the view of Basque's categorical resistance to gender categories.Significance: The study contributes to theories of structural permeability by demonstrating how core functional domains are reshaped under sustained pressure, offering a model for how genderless languages develop gender categories through social negotiation.