Fe"tus (?), n.; pl. Fetuses (#). [L. fetus, foetus, a bringing forth, brood, offspring, young ones, cf. fetus fruitful, fructified, that is or was filled with young; akin to E. fawn a deer, fecundity, felicity, feminine, female, and prob. to do, or according to others, to be.] The young or embryo of an animal in the womb, or in the egg; often restricted to the later stages in the development of viviparous and oviparous animals, embryo being applied to the earlier stages. [Written also fœtus.]

• (US) An unborn or unhatched vertibrate that is showing signs of the mature animal; an unborn baby after the 7th week of gestation.