borrowed from New Latin, from Greek deinós
“inspiring dread or awe” + -o--o-
+ New Latin Sauria sauria
The taxonomic name Dinosauria as well as the vernacularization dinosaur were both introduced by the British biologist and paleontologist Richard Owen (1804-92) in “Report on British Fossil Reptiles. Part II,” Report of the Eleventh Meeting of the British Association for the Advancement of Science (“Held at Plymouth in July 1841”) (London: J. Murray, 1842), p. 103: “The combination of such characters, some, as the sacral ones [i.e., the sacral vertebrae fused into a single structure], altogether peculiar among Reptiles, others borrowed, as it were, from groups now distinct from each other, and all manifested by creatures far surpassing in size the largest of existing reptiles, will, it is presumed, be deemed sufficient ground for establishing a distinct tribe or sub-order of Saurian Reptiles, for which I would propose the name of Dinosauria. [Footnote to the above] Gr. deinòs, fearfully great; saúros, a lizard.” Although Owen’s “Report on British Fossil Reptiles” purports to be the record of an oral presentation given at Plymouth in July, 1841, the detailed contemporary accounts of Owen’s lecture do not mention dinosaur or Dinosauria, and it is now clear that he only introduced the word with the extensively revised version of the report released in April, 1842. The background to Owen’s report is thoroughly analyzed by Hugh S. Torrens in “Politics and Paleontology: Richard Owen and the Invention of Dinosaurs,” M.K. Brett-Surman, et al., editors, The Complete Dinosaur, 2nd edition (Indiana University Press, 2012), pp. 25-43. Offprints of Owen’s article have the publication date 1841, but, as Torrens convincingly demonstrates (p. 34), this was an error (perhaps deliberately uncorrected by Owen). Owen’s rendering of Greek deinós (a word with a wide semantic range) as “fearfully great” is remarkably at odds with the conventional notion that dinosaur means “terrible lizard” in Greek. Although “terrible” (i.e., terrifying) is a possible translation of deinós, it is not the meaning Owen intended.