teratology
noun
ter·a·tol·o·gy ˌter-ə-ˈtä-lə-jē 
: the study of malformations or serious deviations from the normal type in developing organisms
teratologist
ˌter-ə-ˈtä-lə-jist
noun 
Word History
Etymology
borrowed from French tératologie, from Greek terat-, téras "sign sent by the gods, portent, marvel, monster" + French -o- -o- + -logie -logy — more at terato-
Note: As a term in the life sciences introduced by the French zoologist Isidore Geoffroy Saint-Hilaire (1805-61) in "De la nécessité et des moyens de créer pour les Monstres une nomenclature rationelle et méthodique," Annales des sciences naturelles, tome 20 (1830), p. 326. It is uncertain if Geoffroy Saint-Hilaire was aware of the ancient Greek word teratología "account of marvelous things, marvelous tales," formed from the same elements but with an entirely different sense.
First Known Use
circa 1842, in the meaning defined above
Medical Definition
teratology
noun
ter·a·tol·o·gy ˌter-ə-ˈtäl-ə-jē
plural teratologies
: the study of malformations or serious deviations from the normal type in organisms