The principles of simplification/complication of definitions are analysed. It is proved structure of definitions without the generic terms available to children of preschool age. The principles of creation of the explanatory dictionary for children with different extent of cognitive development are proved.
The methods of definition construction are classified according to the information contained in them about relation of defined concept toward to the extension of contiguous concepts. The concepts are evaluated based on their informativeness and the number of words in them. Expediency of using different definitions is analysed for different aims. Drawn conclusion about expedience of the use of features of different definitions in planning of dictionaries constrution.