This glossary was compiled and edited by volunteer scientists from multiple scientific disciplines using reputable sources, including the references listed at the bottom of this page. If you don’t find the scientific word, term, or expression you are looking for, let us know in the comment section below, and we will research the word for you, and add it to the glossary. We desperately need editors to flesh this glossary out. If you are interested, please contact jerry.cates@entomobiotics.com:


  • declivity (de-KLEV-i-tee): L. declivis = bent or inclined downwards, sloping; 1. zool. anat. —sloping downward.
  • deflexed: bent downward.
  • dentate (DEN-tat): L. dentatus = with teeth; 1. zool. anat. — toothed, or with toothlike projections.
  • denticles (DEN-ti-kahls): L. denticulum = little tooth; 1. zool. anat. — small teeth.
  • denticulate: with tiny toothlike projections.
  • depressed: flattened, from top to bottom.
  • diad (DYE-add): Gr. δι- “di” = pref. two-, double- + Gr. -αδ “ad” = suf. -‘to’, toward, near; 1. arach. anat. — a pair of two contiguous eyes.
  • diaxial (dye-AXE-ee-uhl) (= labidognathous, q.v.): L. dis- = pref. between, away from- + L. axis = an axle, axis; 1. arach. anat. — downward projecting chelicerae with the fangs operating along the transverse axis (functioning like ice hooks used to grasp and lift blocks of ice); present in Araneomorphae; compare with the orthogonal chelicerae of Mygalomorphae.
  • dichotomous (dye-KAH-tum-us) key: Gr. διχα “dicha” = in two, in two ways, asunder, apart, at variance; 1. zool. anat. — a listing of diagnostic characters for use in identifying organisms to various taxonomic levels, with the characters so arranged that gross characters are diagnosed first, whereupon successive diagnoses become more refined, following a process whereby each decision point offers the diagnostician two choices; on making a particular choice, the diagnostician either arrives at the organism’s identity, or is directed onward to one or more sets of alternative decision points.
  • digitiform (dij-IT-uh-fohrm): L. digitus = a finger or toe + L. forma = shape, form, beauty; 1. zool. anat. — finger-like.
  • dionychous (DYE-oh-NYE-kuhs): Gr. δι- “di” = pref. two-, double- + Gr. ονυξ “onych” = a talon, claw, nail, hoof; 1. arach. anat. — having two tarsal claws.
  • divergent (dye-VURG-unt): L. divertere = to turn different ways; mod. L., middle Fr.: proceeding in different directions from each other, or from a common point; departing more widely from one another; diverging; 1. zool. anat. — structures whose distance apart increases with distance from a point of relative proximity.
  • distad (DIS-tad): towards the end farthest from body or base.
  • distal (DIS-tul) (also distad; = apical, apicad): L. distare, to stand apart; 1. zool. anat. — in the direction of the terminus of an appendage, away from the body; near or pertaining to that part farthest from body.
  • diverticula (DYE-vur-TIH-kyoo-lah): L. diverticulum = a by-way; 1. zool. anat. — extensions of the digestive system.
  • distitarsus (DIS-teh-TAHR-suhs), pl. distitarsi: see tarsus.
  • dorsad (DOOR-sadd): toward the top or back.
  • dorsal (DOOR-sull) (also dorsum): L. dorsum = the back, ridge, ledge; 1. zool. anat. — the upper surface, i.e., toward the top; pertaining to the back or upper side; top or uppermost;
  • dorsal groove — see fovea.
  • dorsocentral bristles: a longitudinal row of bristles on the mesonotum, just toward the side from the acrostichal bristles (Diptera).
  • dorsolateral: above and to one side.
  • dorsomesal (dohr-so-MEE-suhl): L. dorsum = the back, ridge, ledge + Gr. μεσος “mesos” = middle, in the middle; zool. anat. — toward the middle of the top of the body or appendage.



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).


  1. Allaby, Michael, Ed. 1991. The Concise Oxford Dictionary of Zoology. Oxford Press.
  2. Beccaloni, Jan. 2009. Arachnids; Glossary, p. 319. University of California Press, p. 56.
  3. Borror, Donald J. & Richard E. White. 1970. Peterson Field Guides: Insects. Houghton Mifflin.
  4. Gertsch, Willis J., 1979. American Spiders, 2nd Edition: Glossary, pp. 255-260. Von Nostrand Reinhold Company.
  5. Howell, W. Mike, and Ronald L. Jenkins. 2004. Spiders of the Eastern United States; Glossary, Chapter X, pp. 341-348. Pearson Education.
  6. Jackman, John A. 1997. A Field Guide to Spiders & Scorpions of Texas: Glossary pp. 173-177. Texas Monthly.
  7. Kaston, B. J. 1978. How to know the spiders: Index and Pictured Glossary, pp. 267-272. McGraw Hill Company.
  8. Preston-Mafham, Rod. 1996. The Book of Spiders and Scorpions; Glossary, pp. 140-141. Barnes & Noble Books, New York.
  9. 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.
  10. Venes, Donald, Ed. 2009. Taber’s Cyclopedic Medical Dictionary, 21st Ed. F.A. Davis Company, Philadelphia.
  11. Williams, Tim. 2005. A Dictionary of the Roots and Combining Forms of Scientific Words. Squirrox Press, Norfolk, England.


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