placebo |pləˈsēbō|noun ( pl. -bos) a harmless pill, medicine, or procedure prescribed more for the psychological benefit to the patient than for any physiological effect: his Aunt Beatrice had been kept alive on sympathy and placebos for thirty years [as adj. placebo drugs. • a substance that has no therapeutic effect, used as a control in testing new drugs. •figurative a measure designed merely to calm or please someone. ORIGIN late 18th cent.: from Latin, literally ‘I shall please,’ from placere ‘to please.’ libido |ləˈbēdō|noun ( pl. -dos) ****** desire: loss of libido | a deficient libido. •Psychoanalysis the energy of the ****** drive as a component of the life instinct. DERIVATIVES libidinal |-ˈbidn-əl| adjective libidinally |-ˈbidn-əlē| adverb ORIGIN early 20th cent.: from Latin, literally ‘desire, lust.’