New dictionary words start from a single individual to the rest of the world. When you form a word with a meaning that you deem and use it often in writing and speech, Others pick it up too. If the word spread so much so that it gets cited by dictionary editors, there's probability of it getting into the dictionary. After reading and marking the word, it is cited with the source and when there's citation from various sources, there's higher probability of it being added into the dictionary. This is how words like frenemy and webisode became dictionary words. You can also creat your own word and if others find it good enough to reuse often, it becomes a thing.