Arachnida

2 definitions found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Arachnida \A*rach"ni*da\, n. pl. [NL., fr. Gr. ? spider.]
     (Zool.)
     One of the classes of Arthropoda. See Illustration in
     Appendix.
     [1913 Webster]
  


     Note: They have four pairs of legs, no antenn[ae] nor wings,
           a pair of mandibles, and one pair of maxill[ae] or
           palpi. The head is usually consolidated with the
           thorax. The respiration is either by tranche[ae] 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.
           [1913 Webster]

From WordNet (r) 2.0 [wn]:

  Arachnida
       n : a large class of arthropods including spiders and ticks and
           scorpions and daddy longlegs; have four pairs of walking
           legs and no wings [syn: {class Arachnida}]