arachnid

noun

arach·​nid ə-ˈrak-nəd How to pronounce arachnid (audio)
-ˌnid
: any of a class (Arachnida) of arthropods comprising chiefly terrestrial invertebrates, including the spiders, scorpions, mites, and ticks, and having a segmented body divided into two regions of which the anterior bears four pairs of legs but no antennae
arachnid adjective

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The term arachnid refers to a class of animals that includes spiders, scorpions, mites, and ticks. Most arachnids have a segmented body divided into two regions, with the front part bearing four pairs of legs, but no antennae. They have a hard external skeleton and range in size from the mite, which is 0.003-in (0.08-mm) long, to the 8-in (21-cm) black scorpion of Africa. As arachnids grow, they molt, or shed their skin, several times. Arachnids are primarily carnivorous, but most are unable to digest food internally, instead they inject their prey with digestive fluids, then suck the liquefied remains. Arachnids are found worldwide in nearly every habitat. Some mites and ticks are parasitic and can carry diseases. Venomous spiders and scorpions also may pose a danger to humans, but most arachnids are harmless and prey only on insects.

Examples of arachnid in a Sentence

Spiders, scorpions, mites, and ticks are arachnids.
Recent Examples on the Web In the diverse world of arachnids, black widow spiders, scientifically categorized in the genus Latrodectus, stand out for their distinct appearance and the notorious potency of their venom. Jake Parks, Discover Magazine, 13 Feb. 2024 Tarantula mating season starts early amid threats to arachnids. Ryan Fonseca, Los Angeles Times, 12 Oct. 2023 All spiders are arachnids, but not all arachnids are spiders. Lisa Deaderick, San Diego Union-Tribune, 23 Sep. 2023 The theme followed her onto the carpet in the form of a cobweb dress and sparkly spider earrings, and even her beauty look contained a nod to arachnids: spider lashes. Marci Robin, Allure, 12 Sep. 2023 Despite noble false widow spiders’ taste for large prey, Dunbar doubts the arachnids will ever pose a serious threat to vertebrates such as pygmy shrews. Jack Tamisiea, Scientific American, 16 Mar. 2023 While many species of arachnids are venomous, scorpions boast an especially potent venom cocktail. Scott Travers, Forbes, 28 Feb. 2024 One of America’s newest arachnids—the black and yellow Joro spider, a species endemic to Eastern Asia—has been expanding its range across the Southeast since it was first confirmed stateside in 2014. Christian Thorsberg, Smithsonian Magazine, 26 Feb. 2024 Sea spiders often have eight legs and resemble arachnids, but sea spiders are not actual spiders. Eric Lagatta, USA TODAY, 20 Feb. 2024

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

Word History

First Known Use

1826, in the meaning defined above

Time Traveler
The first known use of arachnid was in 1826

Dictionary Entries Near arachnid

Cite this Entry

“Arachnid.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/arachnid. Accessed 19 Mar. 2024.

Kids Definition

arachnid

noun
arach·​nid ə-ˈrak-nəd How to pronounce arachnid (audio)
-ˌnid
: any of a class of arthropods including the spiders, scorpions, mites, and ticks and having a segmented body divided into two regions of which the front part bears four pairs of legs but no antennae
arachnid adjective

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