The article is devoted to the definition as the main means of term semantization and systematization of terminological knowledge in specialized dictionaries. Among all the ways of explanation and fixation of term semantics the definition is more predominant and significant. The aim of this research is a comparative study of the definition as the main means of semantization in dictionaries of linguistic terms in Kazakh, Russian and English. Semantization in scientific and technical lexicography is defined as a semantic, logical-conceptual analysis, which includes all the possible ways of disclosure of the term meaning in a specialized dictionary. In terminology the definition may not exist in isolation. It is considered as a part of the info...