Abstract: This article examines the analytical approach towards expressing the category of certainty / uncertainty in Slovenian fiction. The analytical forms are comprised by the unchangeable article-type particle “ta”, which is commonly used in the Slovenian colloquial language, but at present is also actively used in the literary language. Special attention is given to the modern Slovenian fiction. The author analyzed ten Slovenian novels published between 2008 and 2018, and revealed all instances of using the article-type particle with both, substantive adjectives and together with adjectives and nouns. The following conclusions were formulated: colloquial elements in fiction perform a stylistic function; therefore one of the key tasks of the article-type particle consists in speech characteristic of the character, including indicating his dialect, since all instanced of using the particle are in the dialogical speech or first-person narrative. However, it is important to note that in most instances, the particle is used with substantive adjectives, which indicates lexicalization of combination of the particle and the adjective, which is used for mentioning a known person/object or indicating a characteristic feature.