Placebo/nocebo terminology

PlaceboThe word placebo is the Latin term for “I shall please.” It is used to indicate sham treatments or inert substances such as sugar pills or saline infusions.
Placebo effectThe placebo effect is defined as any improvement in a symptom or physiologic condition of subjects after placebo treatment. There are different mechanisms underlying this phenomenon, including spontaneous remission, regression to the mean, natural course of a disease, biases, and placebo responses.
Placebo responseThe placebo response refers to the outcome caused by a placebo manipulation. It reflects the neurobiological and psychophysiological response of an individual to an inert substance or sham treatment and is mediated by various factors within the treatment context. Importantly, placebo responses are not restricted to placebo treatments—they can also modulate the outcome of any active treatment.
Active placeboAn active placebo is a substance or treatment that mimics the side effects of the active compound being tested and is thus by definition not an inert substance. In clinical trials, active placebos are administered to avoid un-blinding due to the different side-effect profiles of drugs and placebo treatments.
NoceboThe term nocebo (I shall harm) was introduced in contrast to “placebo” to distinguish the positive from the noxious effects of placebos, when an inert substance is given within a negative context, inducing negative expectations about the outcome.