Glossary of Scientific Terms and Expressions: B

— is a VIEWER-PARTICIPANT WEBSITE.Click on the link for information on what that means. This glossary was compiled and edited by Jerry Cates, using multiple sources, including the references listed at the end of this article:

A – B – C – D – E – F – G – H – I – J – K – L – M – N – O – P – Q – R – S – T – U – V – W – X – Y – Z

  • ballooning: 1. arachnids: spiders —  extruding a silk thread, commonly by recently hatched spiderlings, into space so that it is caught by prevailing winds that lift the spider and propel it through the air, often spanning long distances before the spider lands, thus efficiently dispersing the fliers from their birth sites to other locales.
  • basal (basad) = proximal (proximad): L. basis = base, pedestal,  and Gr. βασις “basis” = base, foundation wall, step; 1. anatomy— toward the body or the base of an appendage.
  • basitarsus (pl. basitarsi) = metatarsus (q.v.)
  • bidentate (by-DEN-teyt): L. bis = twice, double + L. dentatus = with teeth; 1. anatomy — with two teeth.
  • bifid = bifurcate (q.v.)
  • bifurcate (BY-fuhr-kaht) = bifid: L. bis = twice, double + L. furca = a two-pronged fork; 1. lanatomy — two-pronged.
  • bipartite (by-PAHR-teyt): L. bis = twice, double + L. partir = to divide; 1. anatomy — in two parts, split into two sections.
  • biseriate (by-SEHR-ee-at): L. bis = twice, double + L. serere = to place in a row; 1. anatomy — arranged in two parallel rows.
  • Blumenthal’s tarsal organ (see tarsal organ)
  • book lung: 1. arachnids — a respiratory structure, lying ventrally in the anterior opisthosoma,  comprised of a rounded cavity filled with stacks of leaf-like, large-surface-area organs (thin, gas-permeable lamellae, filled with circulating blood), that bring inspired air into intimate, though indirect contact with the arachnid’s hemolymph (blood), thus allowing for efficient gas exchange; air is drawn in and exhaled through a posterior lung slit in the book lung cover; 1.a. araneids —  Araneomorphae have one pair of book lungs positioned anterodorsally of the epigastric furrow; by comparison, most Mygalomorphae and Hypochilidae have a second pair posterior of the epigastric furrow.
  • book lung cover (= brachial operculum): 1. arachnids — the sclerotized plate on the ventral abdomen that covers the book lung.
  • boss (= condyle): 1. arachnids: spiders — a rounded swelling, a smooth bump or protuberance, located at the lateral angle of the base of the chelicera of certain species of spiders.
  • branchial operculum (= book lung cover, q.v.)
  • bristle: 1. arachnids: anatomy — a long, thin extension of the cuticle (i.e., not articulated in a socket, as are setae), more slender than a spine.
  • bulb (= bulbus = genital bulb = palpal organ): 1. arachnids: spiders — the genital structure of the male spider containing the sperm reservoir and attached to the palpal tarsus; rarely, as in some Oonopidae, the bulb is fused to the tarsus, from which it can be distinguished by its absence of setae.



  • anat. = anatomy; arach. = arachnid; behav. = behavioral; biol. = biological (inclusive of all animals and plants); bot. = botanical (inclusive of all plants); Gr. = Greek; L. = Latin; q.v. = L. quod vide = which see; pl. = plural; taxon. = taxonomy; zool. = zoological (inclusive of all animals).



  • Allaby, Michael, Ed. 1991. The Concise Oxford Dictionary of Zoology. Oxford Press.
  • Beccaloni, Jan. 2009. Arachnids; Glossary, p. 319. University of California Press, p. 56.
  • Gertsch, Willis J., 1979. American Spiders, 2nd Edition: Glossary, pp. 255-260. Von Nostrand Reinhold Company.
  • Howell, W. Mike, and Ronald L. Jenkins. 2004. Spiders of the Eastern United States; Glossary, Chapter X, pp. 341-348. Pearson Education.
  • Jackman, John A. 1997. A Field Guide to Spiders & Scorpions of Texas: Glossary pp. 173-177. Texas Monthly.
  • Kaston, B. J. 1978. How to know the spiders: Index and Pictured Glossary, pp. 267-272. McGraw Hill Company.
  • Preston-Mafham, Rod. 1996. The Book of Spiders and Scorpions; Glossary, pp. 140-141. Barnes & Noble Books, New York.
  • Ubick, D., P. Paquin, P.E. Cusing and V. Roth, editors, 2005. Spiders of North America, Chapter 72: Glossary — pronunciation guide. Published by the American Arachnological Society.
  • Venes, Donald, Ed. 2009. Taber’s Cyclopedic Medical Dictionary, 21st Ed. F.A. Davis Company, Philadelphia.
  • Williams, Tim. 2005. A Dictionary of the Roots and Combining Forms of Scientific Words. Squirrox Press, Norfolk, England.

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