What does arachnid mean?
An arachnid is any member of Arachnida, a class of joint-legged invertebrate animals that includes spiders, scorpions, ticks, mites, and harvestmen. Arachnids are characterized by having eight legs, a body divided into two sections (the cephalothorax and abdomen), and no antennae or wings — features that clearly distinguish them from insects, which have six legs and three body segments. The word is used both in formal scientific writing and in ordinary conversation whenever someone wants to refer to this whole group collectively rather than to a single species like a spider. Because many people find these creatures unsettling, "arachnid" frequently appears alongside discussions of fear, most famously in "arachnophobia." The term traces back through Latin to Greek mythology, where Arachne, a skilled weaver, was transformed into a spider after challenging the goddess Athena — making the word's origin as memorable as the creatures it describes.
nounA member of the class Arachnida: an eight-legged arthropod such as a spider, scorpion, tick, or mite, whose body is divided into two main parts and which lacks antennae.
- Any eight-legged arthropod of the class Arachnida, including spiders, scorpions, ticks, and mites.
"The cellar was home to every kind of arachnid — spiders, harvestmen, and at least one scorpion."
"Ticks and mites are among the most numerous arachnids on Earth."
"She recoiled when she spotted the arachnid lurking in the bathtub."
Regular plural; used when referring to multiple members of the class or to the class as a whole.
"Deserts are home to a surprising variety of arachnids."
Spiders aren't insects — they're arachnids, a class named after a Greek weaver who was turned into a spider for daring to out-spin the goddess Athena.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of arachnid
The word "arachnid" comes from the modern Latin "Arachnida," itself derived from Greek "aráchnē," meaning spider. In Greek mythology, Arachne was a Lydian weaver so skilled that she challenged the goddess Athena to a contest; according to Ovid's account, she was ultimately transformed into a spider for her hubris. The English word entered use around the early nineteenth century, when naturalists formalized the class name, though related forms such as "arachnoid" appeared earlier. Cognates include "arachnophobia" (fear of spiders) and the adjective "arachnoid," used in anatomy for structures with a spiderweb-like appearance.
How arachnid is actually used
"Arachnid" is a scientific term used in both formal zoological writing and general speech. It carries no strong connotation, though it often appears in contexts of fear or revulsion (as in "arachnophobia"). In everyday conversation people usually say "spider"; "arachnid" is chosen when referring broadly to spiders, scorpions, ticks, and mites as a group.
Easily confused with arachnid
Insects have six legs, antennae, and typically three body segments, whereas arachnids have eight legs, no antennae, and two body segments.