any wingless, carnivorous arthropod of the class Arachnida, including spiders, scorpions, mites, ticks, and daddy-longlegs, having a body divided into two parts, the cephalothorax and the abdomen, and having eight appendages and no antennae.
1869, from Fr. arachnide (1806) or Mod.L. Arachnida, introduced as name for this class of arthropods 1815 by Fr. biologist Jean Baptiste Pierre Antoine de Monet de Lamarck (1744-1829), from Gk. arakhne "spider," which probably is cognate with L. aranea "spider, spider's web" (from aracsna).
(ə-rāk'nĭd) Any of various arthropods of the class Arachnida, such as spiders, scorpions, mites, and ticks. Arthropods are characterized by four pairs of segmented legs and a body that is divided into two regions, the cephalothorax and the abdomen.