Based on own data (results and generalizations), exhaustive comprehensive approaches to the definition of the term of "lectins" and the formation of a working definition of lectins are proposed and discussed. A comprehensive analysis of the conceptual ideas about lectins has been carried out. The sum systemic current working definition of the term of "lectins" is formulated, including the most important features of these proteins that recognize and bind carbohydrates and glycoconjugates. The proposals will help experimenters in developing their own relevant methodology for studying lectins, which is closest to fulfilling the mandatory specific conditions of the experiment, and will also help to take a balanced approach to obtaining and further developing promising results in biology and medicine.