In this article, Ukrainian encyclopedias are studied in order to show how they describe the capture of Crimea by the Russian Federation. The authors focus on terms describing the act of aggression of the RF against the Ukrainian peninsula, such as “annexation” and “occupation”. The fact is that there is still no terminological clarity among scholars, therefore, it is not easy to interpret both the events of spring 2014 and the political and legal consequences of these events. The fact is also that scholarly studies of these problems are a contribution to the formation of the policy for Ukrainian Crimea de-occupation. Results of the article show that in some encyclopedias the terms “annexation” and “occupation” are actually used interchangeably, referring to the Russian invasion of Crimea and the capture of this territories by RF. In others, differences in the meaning of these concepts are presented: the occupation of Crimea is called a violation of the territorial integrity of Ukraine by the RF; the annexation of Crimea is the illegal annexation of the occupied territories by the RF.