Definition

1. Noun (Biology/Taxonomy):
   • A major taxonomic class within the phylum Arthropoda, comprising air-breathing invertebrates characterized by having four pairs of walking legs, a body divided into two main segments (the cephalothorax and the abdomen), and no antennae or wings. This class includes spiders, scorpions, ticks, mites, and harvestmen.

Usage Examples

• Noun:
  • Spiders and scorpions both belong to the class Arachnida.
  • The study of the class Arachnida is called arachnology.
  • Ticks, which are parasites, are also members of class Arachnida.

Advanced Usage

• "Arachnida" as a taxonomic rank: The term is used in formal scientific classification. It is often capitalized when referring to the formal class name: .
  • The order Araneae (spiders) falls under the class Arachnida.

Variants and Related Words

• Arachnid (n): A common term for any member of the class Arachnida.
  • Spiders are the most familiar type of arachnid.
• Arachnological (adj): Relating to the study of arachnids.
  • The arachnological society published new research.
• Arachnology (n): The scientific study of spiders and related organisms in the class Arachnida.
  • She pursued a degree in arachnology.

Synonyms

• Chelicerates (n): A broader subphylum (Chelicerata) that includes class Arachnida along with other classes like Merostomata (horseshoe crabs). While not a perfect synonym, it is a closely related taxonomic term.
  • Arachnids are a diverse group of chelicerates.

Notes on Different Meanings

• The term "class Arachnida" has a single, specific meaning in scientific (zoological) context. It does not have common idiomatic or figurative uses outside of biology.

Noun

1. a large class of arthropods including spiders and ticks and scorpions and daddy longlegs; have four pairs of walking legs and no wings