The Explanatory Dictionary of Russian Everyday Speech is one of the first attempts to describe everyday vocabulary in a dictionary. Given the specifics of colloquial speech, this is not a very simple task. The article describes how the glossary of this dictionary was formed, words of what kind were included in it, which principles of word selection, i.e. which criteria for colloquiality, were used by the authors. Among the latter, the following are listed: the functioning of a word in a spontaneous, casual oral speech, and the a possible (or obligatory) existence of a neutral synonym or a lexical equivalent for the word, the presence of specific (emotionally colored) suffixes, a metaphorical transfer as a way of nominating words, expressive coloring and / or word evaluation. The article also addresses the question why representatives of different generations can feel the stylistic reference of a certain word in different ways. It is suggested that this is influenced primarily by the experience of using the word – the less familiar a word is to native speakers, the less colloquial it seems to them; on the contrary, they perceive it as a neutral or bookish. The article also considers the difficulties the authors of the dictionary faced in describing the colloquial vocabulary.