Take a side in an argument that is the opposite of what you really want or think.
A translation of the Latin phrase advocatus diaboli.
Devil’s advocate is the popular name for the official in the Roman Catholic Church who puts the case against a candidate for canonization or beatification. He is more properly known as promoter fidei promoter of the faith.
1994 Jude Deveraux : The Invitation : She had played devil's advocate with herself a thousand times.