'To sing placebo' definitions:

Definition of 'To sing placebo'

From: GCIDE

Placebo \Pla*ce"bo\, n. [L., I shall please, fut. of placere to please.]
1. (R. C. Ch.) The first antiphon of the vespers for the dead. [1913 Webster]
2. (Med.) A prescription with no pharmacological activity given to a patient to humor or satisfy the desire for medical treatment. [1913 Webster]
3. (Med.) a dose of a compound having no pharmacological activity given to a subject in a medical experiment as part of a control experiment in a test of the effectiveness of another, active pharmacological agent. [PJC]
To sing placebo, to agree with one in his opinion; to be complaisant to. --Chaucer. [1913 Webster]