nounpl. no·ce·bos, or no·ce·boes
A substance that causes undesirable side effects as a result of a patient's perception that it is harmful rather than as a result of a causative ingredient.
Origin of noceboLatin nocēbō I will harm first person sing. future tense of nocēre to harm (on the model of placebo ); see nek-1 in Indo-European roots.