• Webster's Revised Unabridged Dictionary
    • n Pygidium (Zoöl) The caudal plate of trilobites, crustacean, and certain insects. See Illust. of Limulus and Trilobite.
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Century Dictionary and Cyclopedia
    • n pygidium A posterior part of the body, in any way distinguished; an anal, caudal, or pygal part or organ: said chiefly of insects, crustaceans, and worms. In entomology, the last dorsabdominal segment, when modified or specialized, as into an ovipositor, sting, anal forceps or cerci, etc. The term is much used in the classification of coleopters, hymenopters, and some of the homopters. In Coleoptera, the term generally applies to any part of the dorsabdominal segments which may be visible beyond the ends of the closed elytra. This is usually harder than the part covered by the elytra. When more than one segment is thus exposed, pygidium may be restricted to the last one, the next preceding being distinguished as propygidium.
    • n pygidium [capitalized] A genus of nematognaths, typical of the family Pygidiidæ. Later called Trichomycterus.
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Webster's Revised Unabridged Dictionary
NL., fr. Gr. , dim. of the rump


In literature:

Abdomen beneath yellow, each segment margined with brown, the pygidium yellow, with two largish oblique black spots.
"Discoveries in Australia, Volume 1." by J Lort Stokes
The relation in size between the flea and its pygidium.
"Scientific American Supplement, Vol. XIX, No. 470, Jan. 3, 1885" by Various
Median notch: in Coccidae, a notch in the edge of the pygidium, at the posterior extremity of the body.
"Explanation of Terms Used in Entomology" by John. B. Smith