- A class of arthropods that includes spiders, scorpions, mites, and ticks.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
Examples from the Web for arachnida
The balance is preserved by a corresponding number of Arachnida.
Contributions to the knowledge of the life history of Arachnida.The Biotic Associations of Cockroaches
Louis M. Roth
Arachnida (, spider) is the Class of spiders, scorpions, and mites.An Elementary Text-book of the Microscope
John William Griffith
Her prey was some hideous Scorpion, that first-born of the Arachnida.Bramble-bees and Others
J. Henri Fabre
Coxal glands have since been recognized and described in other Arachnida.