Douglas Harper's Etymology Dictionary
Wiktionary
a. Intended to ward off evil. n. An agent intended to ward off evil.
WordNet
adj. having the power to prevent evil or bad luck
Usage examples of "apotropaic".
Hens and geese scavenged beneath the patched mud walls, on which apotropaic religious symbols were painted.
Sure, they were draped with so many different lands of apotropaic amulets that they looked like perambulating Christmas trees.
But since you gained the throne, I and my colleagues have hedged you round with far more apotropaic incantations.
All the wizards with the imperial army redoubled their apotropaic spells.
They took to carving an apotropaic symbol on their air-octave stones: one circle inside another, with rays like spokes connecting the inner with the outer.
T suddenly understand the gesundheit-impulse, the salt over the shoulder and apotropaic barn-signs.