Foetus is simply the Latin word for young or offspring.
It is used medically to denote the unborn child from the eighth week of development, before which the term 'embryo' is used. In the UK, when doctor's began killing newborn handicapped children, quite markedly they referred to them as neonates and stoppped calling them babies. It is a consistent tactic of the anti-life lobby to use categorisations in attempts to dehumanise those to be destroyed. It is complete, unique, human and alive. At teh end of week 8 the embryonic period is complete and the foetal period begins.