The article considers the use of diminutives in the language of Russian science in the second half of the 18^th – early 19^th cs. At that time, the use of diminutives as scientific terms was quite a natural phenomenon, words with diminutive suffixes were used in various fields of science, most of them fell into the language of emerging biology. In the language of modern science, many of these terms, which are diminutives in origin, continue to be used, despite the fact that in the language of modern science there is a ban on the use of expressive words, including those with diminutive suffixes. However, this prohibition does not apply to terms that arose in the early period of the formation of the language of Russian science.