arachnology

Arachnology (from Greek: αραχνη, arachne, "spider"; and λόγος, logos, "knowledge") is the scientific study of spiders and related organisms such as scorpions, pseudoscorpions, harvestmen, collectively called arachnids. However, the study of ticks and mites is sometimes not included in arachnology, but is called Acarology. Those who study spiders are arachnologists.
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(n.)
The department of zoology which treats of spiders and other Arachnida.