History of the term “anodyne” in homotopy theory

There is a notion of an anodyne morphism (usually of simplicial sets). This type of morphisms is used, for instance, to establish basic properties of quasicategories. But the name is quite mysterious. Why are such morphisms called anodyne? I checked several sources on simplicial homotopy theory and they all use the word "anodyne" without any explanations. Is there some reason for this particular word to be used for this meaning?

• I believe the phrase is due to Gabriel and Zisman. – Zhen Lin Dec 10 '14 at 20:50