foetus /ˈfiːtəs/ noun3 •An unborn or unhatched vertebrate showing signs of the mature animal. •A human embryo after the eighth week of gestation.The sequence is: molecules in reproductive systems, then gametes, zygotes, morulas, blastocysts, and then fetuses. •(no longer used) A neonate. formsfoeti · foetus · foetuses · foetûs