Definition: Special effects. n. 1 Visual or sound effects introduced into a recorded production. 2. "Cirque du Soleil: Quidam." The effects in "Quidam" are such that you just can't believe the human body can do what you know you're witnessing. And one thing that makes a Cirque show special is there's no skimping; the music and singing is performed live, the costumes are dazzling and the comic relief is a hoot.