How does a non-dictionary word become a dictionary word

There are so many dictionaries and so many words. How do new words appear in dictionaries? If a a word appears in one dictionary can it be counted to be a dictionary word, an official one that anyone can use?

Solution 1:

I am not sure whether your question is on-topic, but "How our dictionaries are created" by Oxford Dictionaries explains:

Before adding a word to one of our dictionaries we have to see evidence that it is widely used in print or online. We tailor entries to suit the needs of the user: a dictionary for children at primary school level, for example, will contain words and definitions appropriate to that age group. (emphasis mine)

Obviously, they have lexicographers and language experts who are monitoring neologisms by means of reviewing corpus, user-generated content, and submissions by dictionary users.

As the above link explains, the dictionary is descriptive rather than prescriptive. Just because one dictionary listed a new word doesn't mean anyone can use it until it gets enough traction and popularity. For example, the word moobs (man + boob) has been newly listed in Oxford English Dictionary which was first recorded in 2001. Is it used by everybody? I doubt it.