arachnid

noun

arach·​nid ə-ˈrak-nəd 

-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

Without a deep freeze, these arachnids and various insect pests don’t die off en masse, Pell says. —Jude Coleman, Scientific American, 22 Mar. 2023

About 40 to 60 species of these arachnids live in the Grand Canyon State, according to the Arizona Department of Agriculture. —Dina Kaur, The Arizona Republic, 21 June 2023

This jet-black arachnid ranges from 0.2 to 0.5 inches in size and are rarely seen. —Cole Sikes Communications and Marketing Specialist Alabama Cooperative Extension System, al, 8 Aug. 2023

Spider monkeys typically consume fruits, leaves, nuts, seeds, and sometimes arachnids and insects. —Amaris Encinas, USA TODAY, 4 Aug. 2023

The parasitic arachnids are also noted to be moving further north and higher in altitude as formerly inhospitable terrain warms to their preferred temperature range. —Time, 28 July 2023

The camel spider, also recognized as a sun spider and wind scorpion, is one of the most unique arachnids of all time and holds captivating secrets. —Jeremy Hillpot, Discover Magazine, 10 June 2023

Hers is one of countless accounts that have fascinated TikTok users who may have previously swatted at or cowered from the misunderstood arachnids. —Scottie Andrew, CNN, 25 Mar. 2023

The hissing happens when arachnids rub their body parts together. —Jeremy Hillpot, Discover Magazine, 10 June 2023

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Word History

First Known Use

1826, in the meaning defined above

Kids Definition

arachnid

noun

arach·​nid ə-ˈrak-nəd 

-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