The author analyzes the convenience of using certain juridical terms in the domain of narcotic, psychotropic substances, their analogues and precursors circulation. The terminological study leads to the conclusion that the notions used in this domain have a marked variety and complexity. The majority of the terms also have extra-juridical connotations, especially medical connotations. As a result of the terms’ polysemy, some doctrinaires and legislators misuse certain terms. An alarming phenomenon is the term dualism, for example, two different terms express the same content. The author opts for the terms used in the international convention, ratified by Republic of Moldova, and also for the terms that have a consistent scientific grounding.