Arachnids are an extremely diverse and fascinating group of animals with over 100,000 known species in around 790 families. With over 6,700 entries, this dictionary for arachnology is the most complete reference work of its kind available today and includes a comprehensive taxonomic coverage of the orders Acarina, Amblypygi, Araneae, Opiliones, Palpigradi, Pseudoscorpiones, Ricinulei, Schizomida, Scorpiones, Solifugae and Uropygi down to the level of family, including many species that are of particular interest. Appendices give a synopsis of the class Arachnida and an alphabetical list of all the families. Arachnology is not studied in isolation, therefore the more common terms from the fields of Anatomy, Animal Behavior, Ecology, Genetics, Taxonomy and Zoogeography, as well as many terms covering sizes, shapes, colors, forms and textures have been included.