|any terrestrial chelicerate arthropod of the class Arachnida, characterized by simple eyes and four pairs of legs. The group includes the spiders, scorpions, ticks, mites, and harvestmen|
|[C19: from New Latin Arachnida, from Greek arakhnē spider]|
|arachnid (ə-rāk'nĭd) Pronunciation Key
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.