A pleonasm is the use of redundant words, often in established phrases or idioms.
I tried to write something, but it's hard to beat this excellent excerpt by the comedian George Carlin from When Will Jesus Bring the Pork Chops — spot the pleonasms:
"My fellow countrymen, I speak to you as coequals, knowing you are deserving of the honest truth. And let me warn you in advance, my subject matter concerns a serious crisis caused by an event in my past history...At that particular point in time, I found myself in a deep depression, making mental errors which seemed as though they might threaten my future plans. I am not over-exaggerating.
I needed a new beginning, so I decided to pay a social visit to a personal friend with whom I share the same mutual objectives and who is one of the most unique individuals I have ever personally met. The end result was an unexpected surprise. When I reiterated again to her the fact that I needed a fresh start, she said I was exactly right; and, as an added plus, she came up with a final solution that was absolutely perfect.
Based on her past experience, she felt we needed to join together in a common bond for a combined total of twenty-four hours a day, in order to find some new initiatives. What a novel innovation! And, as an extra bonus, she presented me with the free gift of a tuna fish. Right away I noticed an immediate positive improvement. And although my recovery is not totally complete, the sum total is I feel much better now knowing I am not uniquely alone.”