Generally, all developing organisms are called embryos until they attain an independent existence. However, in mammals - and especially humans - the term foetus is used when the embryo has reached a stage where most of the adult features can be seen (ears, eyes, cloven feet, tail, fingernails and so on). In humans, this change in name usually takes place at around 8 weeks after conception.
the unborn young of any mammal. In humans, the unborn child is known as a foetus from the eighth week after conception until birth. It is during the foetal stage that the full development of organ systems takes place.
Middle stage of development between an embryo and baby, when all main recognisable features are shown i.e. from the end of the second month of pregnancy. Follicle – Circular fluid filled cavity within the ovary containing a developing egg.
the name used for the unborn baby from the end of the 8 th week after conception (when the major structures have formed) until birth. Up until the eighth week, the developing offspring is called an Embryo.
The unborn child from around eight weeks after conception (when all major organs are formed and it begins to resemble a human being) to the time of birth. (Before then, it's considered an embryo.) The word foetus means "young one."