/plə'si:bəʊ; plə`sibo/
n (pl ~s)
1 (medical 医) harmless substance given as if it were medicine to calm a patient who mistakenly believes he is ill 安慰剂
*[attrib 作定语] placebo effect, ie beneficial effect of taking a placebo 宽慰作用（服安慰剂後的）.
2 thing done or said only to please or humour sb 使人宽慰的事物; 安慰话.

npluralplacebos[C]
[Date: 1700-1800; Language: Latin;Origin:'I shall please', from placere; PLEASE²]
a harmless substance given to a sick person instead of medicine, without telling them it is not real. Placebos are often used in tests in which some people take real medicine and others take a placebo, so that doctors can compare the results to see if the real medicine works properly.
placebo effect
when someone feels better after taking a placebo, even though it has not had any effect on their body