The article is devoted to the study of glossaries as a specific paratextual form that provides interpretative foundations for the study of constructed languages in works of fiction. Based on the novel and graphic novel Watership Down by R. Adams, the article analyzes the lexical and grammatical features and functional principles of the Lapin language, which marks the animal-centered narrative. A review of heterogeneous approaches to the conceptualization of artificial languages in linguistic, literary, and translation studies is provided. The scientific research distinguishes between the terms conlang and artlang. Following J. R. R. Tolkien, the fundamental aspects of language creation are presented. The scope of the novel is outlined from the perspective of the genealogy of narrative works. An etymological analysis of the taxonomy “Lapinsky” is conducted, which directly reflects the unity of the composition of the literary work and the proposed language system. The artlang glossary is examined in terms of the constitutive factors of language, taking into account R. Jakobson's systematics. Using the method of continuous sampling of factual material, as well as descriptive and inductive methods, a lexical-grammatical analysis of the linguistic means of the specified art language was carried out. Particular attention is paid to the study of the derivational models of the Lyapinsky construct, which contributes to a deeper understanding of the linguistic potential. The results of the study confirm the importance of reproducing the glossary as a paratextual integrity that forms a correlative pair with the main text and contributes to preserving the sense of unevenness of the textual fabric, making it possible to avoid explication or generalization through the use of the technique of alienation. At the same time, a number of paratextual shifts and paratranslation decisions in the Ukrainian versions of the work are highlighted, in particular, the subordination of art language lexical units to the norms of the target language is traced, and inaccuracies in the representation of honorifics, etc., are emphasized. The study deepens the study of translation strategies in the context of reproducing artificial languages and justifies the glossary as a legitimate way of preserving the linguistic features of the original in the target culture.