It’s certainly possible, depending on exactly how you want to structure it. If you are writing everything yourself you can turn off registration and allow only admin to ask/answer/comment.
If you want it to be user-generated (like Urban Dictionary for example) then a standard Q2A setup might work. Someone makes a question which is the word itself, then others (or the same person) post answers which give a definition for the word. And other users can upvote their favourites.
