One of the activities of the members of Ukrainian human rights and national liberation movement in the 1960– 1970s was the protection of the rights of Ukrainian language for free development and functioning expansion as counteraction to the strengthening of Russification strategy in the USSR. In his journalistic and linguistic works, the human rights activist, dissident, and pedagogue Oleksa Tykhyi raised the problems of preserving and developing Ukrainian language as a major factor of national self-identification. He expressed concern about its status in Ukraine, clearly identified the reasons for this and seeked the ways to improve the situation. The goal of the paper is an attempt to comprehend and illuminate the vocabulary activity of O. Tykhyi, which was closely related to his teaching activity and active civil and ideological position as a defender of Ukrainian language. The paper uses the following methods: descriptive method, contextual analysis and structural analysis of linguistic units. The material of this study was the “Dictionary of Words Inappropriate to the Norms of Ukrainian Literary Language» by Oleksa Tykhyi. It is found out that the words, not compliant with the norms of Ukrainian language and recorded in the vocabulary, include lexical and morphological Russianisms, adoptions from other languages through the Russian language as well as word-forms copied from the Russian language. In general, the vocabulary contains about one and a half thousand lexical units that are not specific to the Ukrainian language, each one is presented with a synonymic number of Ukrainian equivalents. Most of them are lexical Russianisms, i. e. words directly transposed from the Russian language without phonetic adaptation that substituted specific Ukrainian words. Some of them functioned only in spoken language, while others were codified in lexicographic works. A number of Ukrainian synonyms provided to each of the analyzed tokens demonstrates the artificiality and unnecessity of such adoptions. Analysis of the material of the vocabulary of Oleksa Tykhyi shows the negative consequences of Russification for the lexical composition of Ukrainian language and for the level of the language culture of population.