In exploring the multi-dimensional and incremental nature of grammatical change that emerges from the recurrent interaction between a form and its environment, the study demonstrates that a systematic examination of morphological irregularity can enrich our understanding of the anatomy of grammatical change. The empirical focus is the functional crystallization of a particular type of participial adjective (PA) in Old Czech, as manifested in morphologically irregular tokens of this category.
The analysis of their behavior vis-a-vis the regular PAs in comparable environments (clausal vs. adnominal constructions) shows that the two formation types are both sensitive to roughly the same set of features in developing a different functional status (secondary predicate vs. adnominal modifier), but each 'compensates' for the mismatch between its morphology and each syntactic function in a characteristically different way. At the theoretical level, the analysis leads toward clarifying the content of the notion 'constructionalization' as a hypothetically distinct type of change, and offers some thoughts on spelling out the role of constructions in grammatical reorganization.