Superlative adjectives in Slovenian grammar are used to express the highest degree of a quality. They are formed by adding the suffix ”-ji” or ”-naj” to the stem. The stem is the first part of the adjective without the ”-en” ending. For example, the superlative form of ”velik” (big) is ”najveliki” (the biggest). It’s important to note that in Slovenian, the superlative always includes the definite article, producing a translation equivalent to ”the most/biggest” in English.