A word used when patients say they feel better when they have been lied to. Not necessarily lied to, but told they have been given a drug or undergone an operation which would supposedly make them healed, which was not actually done.
I believe you are referring to the placebo effect. A placebo given as medicine is a pill that has no medical effect (it's made of sugar, has no taste, no nutritional value -- it just 'feels' like you're taking a pill.)
It has been scientifically proven that placebos help people recover from illness. This is a counter intuitive result because placebos should have no medical effect. However, they do.