Etymology
Borrowed from Latin fētus (“offspring”).
There is an ontological change when conception occurs. The 23 chromosome and the 23 chromosome oocyte (egg) combine to create a unique human being with 46 chromosomes.
From that point on, that new human being only needs a safe environment, water and nutrition to continue to develop throughout his or her lifetime.
There has been a consensus among embryologists, the scientists who study this, for almost a century, and that consensus has been strengthening over time.
When does human life begin?
https://prolifepages.wordpress.com/2012/09/19/when-does-human-life-begin/