parabiosis, parabiotic 1. Fusion of whole eggs or embryos, as occurs in conjoined twins. 2. Surgical joining of the vascular systems of two organisms. 3. Either the condition of living together, applied variously to mixtures of species of similar habit as man and the rat or to the union of two individual animals; or the condition of symbiosis bet... Found on http://www.wordinfo.info/words/index/info/view_unit/2819/40