42 is not the only answer!!!

The word ‘X’, Latin for "I will please", dates back to a Latin translation of the Bible by Jerome. It was first used in a medicinal context in the 18th century. In 1785 it was defined as a "commonplace method or medicine" and in 1811 it was defined as "any medicine adapted more to please than to benefit the patient", sometimes with a derogatory implication but not with the implication of no effect. ‘X’ were widespread in medicine until the 20th century, and they were sometimes endorsed as necessary deceptions. In 1903 Richard Cabot said that he was brought up to use ‘X’, but he ultimately concluded by saying that "I have not yet found any case in which a lie does not do more harm than good". Beginning in the 1960s, ‘X’ became widely recognized and ‘X’ controlled trials became the norm in the approval of new medications. Later, researchers became interested in understanding ‘X’, rather than just controlling for its effects, and in 2011, a Program in ‘X’ studies was established at the Harvard Medical School.

'X'?

'X'-Placebo