ich·​thyo·​saur ˈik-thē-ə-ˌsȯr How to pronounce ichthyosaur (audio)
: any of an order (Ichthyosauria) of extinct marine reptiles of the Mesozoic specialized for aquatic life by a streamlined body with a long snout, limbs reduced to small fins for steering, and a large lunate caudal fin
ichthyosaurian adjective or noun

Example Sentences

Recent Examples on the Web An original recipe, this delicious American-style IPA derives its name from the state fossil—the ichthyosaur. Outside Online, 12 Nov. 2021 These included ichthyosaurs—dolphin-like reptiles—as well as turtles, fish, ammonites, crabs, mollusks, sharks, and at least one species of crocodyliform. Jeanne Timmons, Ars Technica, 23 Mar. 2023 But not just any ichthyosaur was lost. Gemma Conroy, New York Times, 1 Nov. 2022 At more than 55 feet long, the ichthyosaur was estimated to be the size of a large sperm whale, according to the study released Thursday by the American Association for the Advancement of Science and the Natural History Museums of Los Angeles County. Alexandra Larkin, CBS News, 23 Dec. 2021 The partial skull of an ichthyosaur, an extinct marine reptile, that looked like a swordfish was unearthed in Loma Pedro Luis, Villa de Leyva, in Boyacá, Colombia in the 1970s, according to a study published in the Journal of Systematic Palaeontology. Megan Marples, CNN, 2 Dec. 2021 The team behind this paper has been deflating carcass explosion theories about other whacky ichthyosaur fossils too (pdf). Sarah Zhang, Discover Magazine, 30 Mar. 2012 One hundred to 200 million years earlier, an ichthyosaur---a dolphin-looking marine reptile contemporary to dinosaurs---died and became a fossil. Sarah Zhang, Discover Magazine, 30 Mar. 2012 However, evidence of this dinosaur has always been tied to the much older Triassic period, including evidence of a Triassic period ichthyosaur found by researchers back in 2020. Joshua Hawkins, BGR, 2 Jan. 2023 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'ichthyosaur.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


ultimately from Greek ichthy- + sauros lizard

First Known Use

1830, in the meaning defined above

Time Traveler
The first known use of ichthyosaur was in 1830

Dictionary Entries Near ichthyosaur

Cite this Entry

“Ichthyosaur.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/ichthyosaur. Accessed 2 Jun. 2023.

Kids Definition


ich·​thyo·​saur ˈik-thē-ə-ˌsȯ(ə)r How to pronounce ichthyosaur (audio)
: any of an order of extinct marine reptiles with a fish-shaped body and a long snout

More from Merriam-Webster on ichthyosaur

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!