embryoEnglishOxford American Thesaurusembryo noun 1 the development of the embryo in the uterus: fetus, fertilized egg, unborn child/baby. 2 the building is used as the embryo of a university for the island: rudimentary version, germ, nucleus, seed, root, source; rudiments, basics; beginning, start, basis, mainspring.word linksembryoembryology branch of medicine concerning embryos