When you adduce something, you offer proof in support of an argument. You might adduce the contents of your nearly empty closet in an effort to get your mom to take you clothing shopping.
The word adduce comes from the Latin adducere, which means to lead or bring along. If you were a lawyer, you might adduce, or bring forth, a witness in order to help your case. You might also adduce a piece of evidence, like a fact, to help with your argument. You might think of the word add to help you remember the definition of adduce; when you adduce something, you are adding to an argument by offering proof.