As there are choices with everything in life, there are also choices in the type of dictionary you own. There are two types of dictionaries, and each serves a separate purpose and audience, though few readers know that they are being served differently.
Originally, dictionaries were prescriptive. They focused on the correct usage of the English language, not including nonstandard variants or slang words. The prescriptive dictionaries show the proper usage and accepted spelling of words, suggesting that there are better and worse approaches to using the English language.
Though the prescriptive dictionary gives definite right and wrong answers, most dictionaries today are descriptive.
Descriptive dictionaries describe the English language as it is currently being used. They include all commonly used words, even if they are nonstandard. Some such words are ain’t and irregardless.
A descriptive dictionary would include entries for these words, specifying not only that they are currently substandard but also their definitions when used. A descriptive dictionary keeps the possibility open that substandard words may one day become accepted. Whereas, a prescriptive dictionary would not include entries for substandard words.
Even though most dictionaries are now descriptive, there are levels of the descriptiveness. In choosing a dictionary to work with, be sure you choose one based on your needs.