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 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 But all of these insects and arachnids contribute to the biodiversity of Arizona's landscape. The Arizona Republic, 14 Feb. 2024 The spiders themselves are curious and inquisitive, and they are favored among arachnid admirers for their cleverness and their adorable, almost friendly appearance. Sam Walters, Discover Magazine, 3 Jan. 2024 Like many other cave creatures, these arachnids sport noticeably undeveloped eyes. Jack Tamisiea, Scientific American, 20 Dec. 2023 Colossus, the male funnel-web spider, was the last arachnid to hold the record for ARP's largest male in the antivenom program. Esme Mazzeo, Peoplemag, 5 Jan. 2024 The arachnid lies still, sprawled across the floor with one of its six legs pointed in each direction. Ron Lieber, New York Times, 16 Dec. 2023

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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