Language never stands still. He, like a living organism, obeys the laws of tireless development. Some of its layers significantly change, some are replaced by new ones. Of course, the development of society (changing social structure, hierarchy) and progress in science and technology influence this process.
For a number of words, neither the meaning nor the spelling has changed, but they are uttered differently in modern speech. For example, "music", "symbol." After all, in the 19th century the emphasis was not placed where it was now: they said "music", "symbol". These are phonetically obsolete words. And what is archaism semantic? This is a word that has one or more values that has become obsolete. For example, "not sparing his belly." It's not about a specific part of the body. Once this word meant "life."
What is archaism lexical or lexicon-word-formative? For example, who is the "thief" in the phraseology "aki th in the night"? Once this word meant "thief", now it is used only as part of this idiom, and that is extremely rare. Thieves exist, but the lexeme is obsolete. And here, for example, "friendship" instead of "friendship", "fish" instead of "fisherman" is quite understandable to us, because only the suffixes have changed. This lexicon-word-making archaisms are Russian. We understand that the "dol" is the "valley", "ask" - "ask", but comments are needed to such words as "food" (dishes, food) or "the other day" (on the eve). Nevertheless, archaisms, obsolete words (including historicisms), help the writer to recreate the color of the era. Thus, they play a stylistic role, especially if used in the speech or works of contemporaries. Often to understand what is archaism, the names help (for example, the program "The Other Day" or the word "estate" that is often used in the last few days), and phraseological units in which there are obsolete elements ("seven spades in the forehead" - from " Span "is a measure of length). To understand the meaning of such a name or idiom, we need to refer to a special dictionary (for example, obsolete words and expressions).