New words are added to our lexicon each year. Must we wait until they are in dictionaries before we start using them?

My sisters and I have been using a word that caan only be found in the Urban Dictionary...Plubby, meaning an overweight person.

Not at all - the way those words get into the dictionary is because they are so often used in everyday conversations.

In fact, it's quite the opposite. Lexicographers will not add words until they are quite widespread. Even commonly used words may not be added if they are seen as too limited to a certain region or demographic. 

Dictionaries only exist to record the words we speak. A lexicon exists to record words that people used to speak.