In medicine, a contraindication is a condition (a situation or factor) that serves as a reason not to take a certain medical treatment due to the harm that it would cause the patient.
For example: Relative contraindications are contraindications for circumstances in which the patient is at higher risk of complications from treatment, but these risks may be outweighed by other considerations or mitigated by other measures.
For example, pregnant women should normally avoid getting X-rays, but the risk from radiography may be outweighed by the benefit of diagnosing (and then treating) a serious condition such as tuberculosis.
Which pair is used depends on nomenclature enforced by each organization's style.
The logic of the latter two styles is the idea that readers must never be confused: the word contraindication in that usage always is meant in its absolute sense, providing unmistakable word-sense disambiguation.