How does a word get into the dictionary?

Dictionaries are descriptive, not legislative. Lexicographers monitor enormous collections of published text, called corpora, along with news, books, social media, and specialist writing, watching for words that appear repeatedly across different sources, different contexts, and a sustained period. The criteria are roughly frequency, breadth of use beyond a single community or author, and a meaning stable enough to define. When a term clears those thresholds, editors write an entry with citations documenting its use. There is no committee granting official status, and no word becomes real by being added, since it was already real when people started using it.

This is why dictionaries include slang, profanity, internet coinages, and words plenty of people dislike, including irregardless, which carries a nonstandard label rather than an exclusion. It is also why entries change: definitions get revised as usage shifts, and words get new senses added rather than being corrected. The main exception to pure description is the usage note, where editors flag that a form is contested or considered an error by many readers, which is guidance about social consequences rather than about legitimacy. The Oxford English Dictionary takes the historical approach further, documenting the full life of a word with dated citations, which is why it functions as a record of the language over time rather than a snapshot of current correctness.