Usually, it's because the sperm gets into the fallopian tube before the egg is released. Once there, the sperm wait for an egg to arrive. After fertilization, it can take 5-10 days for the fertilized egg to begin to attach itself to the lining of the uterus. Pregnancy begins when this happens.
The arrangement of spikes originally had no distinct name; the term Thagomizer was coined in 1982 by cartoonist Gary Larson in his comic The Far Side, and thereafter became gradually adopted as an informal term within scientific circles, research, and education.
The English term demigod is a calque of the Latin semideus, half-god, which was coined by the Roman poet Ovid in reference to less important gods, such as dryads. In the ancient Greek and Roman world, the word did not have a consistent definition and was rarely used.