This Dictionary for the first time with the greatest completeness compared to other manuals contains words that cause difficulties in terms of combined, separate or hyphenated spelling. The dictionary is based on the "Rules of Russian Spelling and Punctuation" approved by the USSR Academy of Sciences, the USSR Ministry of Higher Education, the RSFSR Ministry of Education and published in 1956. It is intended as a reference for a wide range of readers. If the word has fluctuations in spelling, the authors chose one option in accordance with the principles set out in the Preface (in the absence of appropriate spelling instructions in the "Rules"). The dictionary will enable philologists based on a lot of material to organize the writing of a number of words that cause controversy and disagreement, and will also help the study of the problem of combined or separate writing.