Abstract
This article examines how morphological anomalies – specifically, the unusually high frequencies of certain singular noun forms – can reveal idiomatic usage in Czech. Using data from the GramatiKat tool, 1,102 noun lemmas were analyzed, of which 28% participated in idiomatic expressions. The study identifies clear distributional patterns across grammatical cases, with idioms most frequent in the accusative, genitive, locative, and instrumental singular. Monocollocational idioms are distinguished, as they are associated with specific structural patterns. The results show that idiomatic expressions can influence morphological distributions and leave measurable traces in corpus data. The approach is further applicable to other parts of speech, such as verbs and adjectives, suggesting a broader role for grammatical profiling in the identification of idiomatic and phraseological patterns.