There are regarded the approaches to nonholophrastic combinations, thus there are compared the phraseology conceptions of V.V.Vinogradov and study of idioms of I.E.Anichkov. There are advanced the arguments that the study of idioms has a greater potential in theoretical and applied aspects. There is shown how study of idioms can be used for semantic definition in a dictionary of the English language and for lexicographical description of the Russian argot.