box jellyfish
noun
variants or less commonly box jelly
: any of various cube-shaped scyphozoan jellyfishes (order or suborder Cubomedusae) of tropical and warm marine waters that inflict a painful and sometimes fatal sting
especially : an extremely venomous box jellyfish (Chironex fleckeri) of Australia that has a bell that may reach over 11 inches (28 centimeters) in width with tentacles that may reach a length of over 78 inches (2 meters) : sea wasp
Found in the waters off northern Australia, the box jellyfish … is not the only marine invertebrate to use venom, but it is the possessor of arguably the most lethal venom in the world. 
Jamie Seymour
Jamie Seymour 
Example Sentences
Recent Examples on the Web The excruciatingly painful sting of a box jellyfish, which can kill a person in under a minute. Elizabeth Hightower Allen, Outside Online, 2 Mar. 2022 You’ve written about the box jellyfish sting, for instance. Elizabeth Hightower Allen, Outside Online, 2 Mar. 2022 In unregulated economies, children are sometimes deputized to harvest box jellyfish for diners. New York Times, 28 Sep. 2021 Not only that, but box jellyfish also distinguish themselves from other species by using sight to keep from bumping into obstacles on the ocean floor. Jason Duaine Hahn, PEOPLE.com, 19 Mar. 2021 The humble box jellyfish, which has wandered the ocean for at least 500 million years, can kill a human in five minutes flat. Corryn Wetzel, Smithsonian Magazine, 30 Oct. 2020 Stings by certain species of box jellyfish, including Irukandji species, have caused deaths in the Indo-Pacific. Michele Chabin, Washington Post, 5 July 2019 Some jellyfish, like the deadly box jellyfish, use toxins that punch holes in skin, blood, and nerve cells alike. National Geographic, 28 June 2018 The analogy here is if Trump argued for the eradication of sharks because of the number of people killed at American beaches — but never talked about the number killed by the box jellyfish. Philip Bump, Washington Post, 19 Jan. 2018 See More
Elizabeth Hightower Allen, Outside Online, 2 Mar. 2022 You’ve written about the box jellyfish sting, for instance. Elizabeth Hightower Allen, Outside Online, 2 Mar. 2022 In unregulated economies, children are sometimes deputized to harvest box jellyfish for diners. New York Times, 28 Sep. 2021 Not only that, but box jellyfish also distinguish themselves from other species by using sight to keep from bumping into obstacles on the ocean floor. Jason Duaine Hahn, PEOPLE.com, 19 Mar. 2021 The humble box jellyfish, which has wandered the ocean for at least 500 million years, can kill a human in five minutes flat. Corryn Wetzel, Smithsonian Magazine, 30 Oct. 2020 Stings by certain species of box jellyfish, including Irukandji species, have caused deaths in the Indo-Pacific. Michele Chabin, Washington Post, 5 July 2019 Some jellyfish, like the deadly box jellyfish, use toxins that punch holes in skin, blood, and nerve cells alike. National Geographic, 28 June 2018 The analogy here is if Trump argued for the eradication of sharks because of the number of people killed at American beaches — but never talked about the number killed by the box jellyfish. Philip Bump, Washington Post, 19 Jan. 2018 See More Word History
Etymology
from its square shape
First Known Use
1960, in the meaning defined above
Medical Definition
box jellyfish
noun
: sea wasp