Human Embryogenesis, Fertilization And Fetus Development

In humans, the fetal stage of prenatal development starts at the beginning of the 11th week in gestational age, which is the 9th week after fertilization.
Etymology and spelling variations
The word fetus (plural fetuses) is from the Latin fetus, meaning offspring, bringing forth, hatching of young. It has Indo-European roots related to sucking or suckling, from the Aryan prefix bheu-, meaning "To come into being".