Plastron

Pronunciation

• IPA: /ˈplæstɹən/

Origin

From French plastron, from Italian piastrone, augmentive of piastra ("breastplate"), from Latin emplastrum ("plaster"), from Ancient Greek εμπλαστρον, from εμπλαστος (emplastos, "daubed, plastered"), from εμπλασσειν (emplassein, "to mould, form").

Full definition of plastron

Noun

1. The nearly flat part of the shell structure of a tortoise or other animal, similar in composition to the carapace.
2. (fencing) A half-jacket worn under the jacket for padding or for safety.
3. An ornamental front panel on a woman's bodice.
• 1942, Rebecca West, Black Lamb and Grey Falcon, Canongate 2006, p. 784,I bought here a wedding dress perhaps twenty or thirty years old ... a sequin plastron to be worn over the womb as a feminine equivalent to a cod-piece, and a gauze veil embroidered in purple and gold.
4. A film of air trapped by specialized hairs against the body of an aquatic insect, and which acts as an external gill.The plastron of a diving beetle is not directly a source of oxygen, but acts as a gill, acquiring oxygen from the surrounding water.
• 2013, Jill Lancaster, Barbara J. Downes, Aquatic Entomology, page 45,Total independence of atmospheric air is possible only if insects have a permanent gas store or incompressible gas gill, called a plastron. Unlike compressible gas stores, the volume of a plastron remains constant and it is incompressible.
• 2013, Jon F. Harrison, Lutz T. Wasserthal (revisions & updates), 17: Gaseous Exchange, R. F. Chapman, Stephen J. Simpson (editor), Angela E. Douglas (editor), The Insects: Structure and Function, 5th Edition, page 535,The plastrons of other insects are generally less efficient than that of Aphelocheirus as they have a less dense hair pile from which the air is more readily displaced.