The present article discusses 36 basic Old Turkic adjectives belonging to the universal semantic types AGE, COLOUR, DIMENSION, HUMAN PROPENSITIES, PHYSICAL PROPERTIES, SPEED, and VALUE (Dixon 1982 [1977]: 15–16). The lexemes will be analysed in terms of their semantic and morphological properties with an emphasis on their primariness. Then, the diachronic stability of the given adjectives will be tested in seven modern Turkic languages: Turkish, Turkmen, Tatar, Kazakh, Uyghur, Khakas, and Yakut.