>And what are the process to “officially” add new words to the language?
Depends on the language. Some languages have a regulatory body (often called an “academy”) which regulates what is and isn’t an “official” word. And among those languages that do have such bodies some are more conservative than others, like French, which does not recognize many words that are in common use by French speakers.
For languages like English, which has no language regulator, there aren’t really “official” words at all. People usually follow major dictionaries like Webster’s or the OED but words they include is completely up to the discretion of the editors/publishers.
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