If something is abridged it means that it has been made shorter/simpler - parts have been left out. Therefore an unabridged dictionary would be a complete dictionary of a language.
You can look at one at a public library. Call first, if your local branch doesn't have one, they can refer you to another library that does. You can buy one online from all of the usual booksellers:...
TO RIDDLE In the description 'unabridged dictionary' it is a tie between "unabridged" and "dictionary", both of which have 10 letters. DICTIONARY ANSWER(S) TO QUESTION There are many contenders for...