ARACHNIDA
Arachnida, class Arachnida
(noun) a large class of arthropods including spiders and ticks and scorpions and daddy longlegs; have four pairs of walking legs and no wings
Source: WordNet® 3.1
A*rach"ni*da, n. pl. Etym: [NL., fr. Gr. (Zoöl.)
Definition: One of the classes of Arthropoda. See Illustration in Appendix.
Note: 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: Araneina, or spiders; Arthrogastra, including scorpions,
etc.; and Acarina, or mites and ticks.
Source: Webster’s Unabridged Dictionary 1913 Edition