title_body: Is there any general rule for constructing a word? Example: "q" or "w" should not end a word, something like this
upvoted_answer: Yes, there are but they are language-specific. These are called phonotactics. They are well explained in the book of David Peterson &quot;The Art of Language Invention&quot;(E-book download link). Actually, these rules include:
  
  structure of a syllable. E.g. in Hawaiian language closed syllables are impossible. So words like &quot;heck&quot; are not allowed. ;)
  
  stress. The Finnish language always stresses the first syllable.
  
  What consonants/vowels can be combined. &quot;st&quot; is quite common in English but not in Hungarian. But &quot;ts&quot; is quite common in Russian but not in English. But on the other hand Russian allows &quot;st&quot; too.
  
  there are many other things. I suggest reading this article on Wikipedia.
  
  
  P.S. I'm not good at linguistic terms in English, sorry for possible wrong use of words ;)