There's a few different dictionaries. There's the official tournament word list (TWL or OWL), which has had different versions. The latest, I believe, is OWL201

There's a few different dictionaries. There's the official tournament word list (TWL or OWL), which has had different versions. The latest, I believe, is OWL2014. I think the version before that was TWL2, IIRC. But those books are only available to tournament scrabble players who pay an annual fee. It's a bit elitist, but that's just how it is (unless it has changed lately). Other than that, you can pick up a regular Scrabble game dictionary, usually called OSPD, which will not have any off-colour words in it. Those can be bought in any book store and you can even search the OSPD on Scrabble's official website.