What does placebo mean?
A placebo is a substance or treatment with no intended therapeutic effect, most often used as a comparison in medical research or as a control for testing a genuine remedy. Its effects are associated with participants' expectations, a phenomenon commonly called the placebo effect: people may report improvement because they believe they are receiving effective treatment. In everyday usage, placebo can also mean a sham medicine or a deceptive substitute presented as genuine care. The term is not necessarily fraudulent, because inactive comparison treatments are an essential part of well-designed clinical trials. Historically, placebos were prescribed partly to reassure patients when no effective remedy was available. Today, the word is common in medicine, psychology, pharmacology, and discussions of experimental design. It can also be used figuratively for any promise or practice whose apparent benefit depends chiefly on belief or suggestion.
An inert substance or treatment used in medical research as a comparison with an active treatment, or administered in the expectation of producing a perceived benefit. It may also refer more generally to a sham remedy or deceptive substitute.
"The trial found that the new drug performed no better than the placebo."
The plural is placebos or placeboes. The technical medical sense is neutral, while everyday use can suggest deception.
Of, relating to, or constituting a placebo or an inactive comparison treatment.
"The researchers conducted a placebo-controlled trial."
Common in compounds such as placebo-controlled, placebo group, and placebo treatment.
To treat someone with a placebo, especially for the purpose of deception.
"The clinic was accused of placeboing patients with ineffective pills."
This verb is rare and occurs chiefly in technical or explicitly critical contexts.
Placebos is standard in general and medical use; placeboes is also an accepted plural.
"Some participants received the active drug, while others received placebos."
Placebo literally meant “I will please” in Latin, originally referring to a treatment prescribed chiefly to satisfy a patient rather than to treat an illness.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does placebo come from?
The word comes from Medieval Latin placebo, literally “I will please,” derived from Latin placere, “to please” or “to seem good.” It was used in medical Latin for a remedy given primarily to satisfy or reassure a patient rather than to produce a genuine therapeutic effect. The modern scientific sense developed with controlled medical experimentation, in which an inactive substance is compared with an active treatment. Its Latin ancestry is reflected in cognates such as placate, placable, placid, and pleasure.
Related word forms
How placebo is actually used
In medicine and research, placebo is a neutral technical term for an inactive comparison treatment. In general use, it may imply deception or false reassurance. The verb form is comparatively uncommon and usually occurs in technical discussion.