Definify.com
Webster 1913 Edition
Arachnida
‖
A-rach′ni-da
,Noun.
pl.
[NL., fr. Gr. [GREEK] spider.]
(Zool.)
One of the classes of Arthropoda. See Illustration in Appendix.
☞ They have four pairs of legs, no antennæ nor wings, a pair of mandibles, and one pair of maxillæ or palpi. The head is usually consolidated with the thorax. The respiration is either by trancheæ or by pulmonary sacs, or by both. The class includes three principal orders: , or spiders; , including scorpions, etc.; and , or mites and ticks.
Araneina
Arthrogastra
Acarina
Definition 2024
Arachnida
Arachnida
Translingual
Proper noun
Arachnida
- A taxonomic class within the subphylum Chelicerata – the spiders, scorpions, harvestmen, mites and ticks, having four pairs of thoracic appendages.
Usage notes
Consensus is lacking for taxonomic classification between the class and order levels. The subclass Acari is sometimes used, but doing so leads to an incompletely specified level.
Hyponyms
- (class): Acari (subclass, no consensus on use)
- Holothyrida, Ixodida, Mesostigmata, Opilioacarida, Sarcoptiformes, Trombidiformes (orders, within Acari when used)
- Amblypygi, Araneae, Opiliones, Palpigradi, Pseudoscorpionida, Ricinulei, Schizomida, Scorpiones, Solifugae, Thelyphonida, Uropygi (= Thelyphonida) (orders)
- †Haptopoda, †Phalangiotarbida, †Trigonotarbida, †Uraraneida (extinct orders)