As a determiner, "one" often functions as a marker of indefiniteness, serving as a way of distinguishing an individual from a group, similar to the way the indefinite article is used in languages that possess it, such as English. However, unlike those languages, the Croatian language does not use articles in the same systematic way, which points to its synthetic nature in which grammatical functions are distributed through inflection, word order and context. By comparing it with English and German, where members have a stable and recognizable role, we come to the realization that the Croatian language uses different strategies to express definiteness and indeterminacy, of which "one" is only one of the elements. The Croatian language, as a synthetic language, often conveys this information through inflection and context, while in analytical languages members take on this role. In conclusion, "one" in the Croatian language has a specific function, which in certain contexts may resemble the use of articles in other languages, but it is not a full-fledged article in the classical sense. Its use largely depends on the context and the need to emphasize individuality or indeterminacy, but it remains deeply integrated into the syntactic and semantic structures of the Croatian language. This research emphasizes the importance of understanding the role of individual language elements within the wider language system, and encourages further reflection on their place in the grammar of the Croatian language.