The story
From sexual mating with a corpse (ie. necrophilia), resulting in viable offspring (ie. functional).
Etymology from Wiktionary, CC BY-SA 4.0.
functional necrophilia
Today it means: A reproductive strategy in some amphibians wherein the male will inseminate a fresh newly-dead female corpse, fertilizing the still viable eggs, and then squeezing the corpse to eject the newly fertilized eggs into the water. Full definition →