Definition of plastron in US English:



  • 1A large pad worn by a fencer to protect the chest.

    • ‘Of course, in addition to the dress itself, is worn the regular fencing outfit of plastron, (or body shield,) padded gauntlet gloves, and centaurs, (or elastic belts).’
    • ‘This is to prevent the mesh from becoming valid target in the event that it comes into contact with any part of the metallic plastron during fencing.’
    1. 1.1historical A lancer's breast covering.
      • ‘The one on the right shows the red plastron worn by this regiment.’
      • ‘His arms are in plate armour, and his body in a shortened hauberk, kept from pressing on his chest, by means of the plastron, or breast-plate, within.’
  • 2An ornamental front of a woman's bodice or shirt consisting of colorful material with lace or embroidery, fashionable in the late 19th century.

    • ‘They are characterized by vivid colors, often edged in black by densely worked plastrons and in particular by net sleeves with wool embroidery.’
    • ‘The woman's dress, with an embroidered plastron (bodice) worn over a wide-sleeved shirt and embroidered Hennin, is typical of the Jewish women of Constantine.’
    1. 2.1 A man's starched shirtfront without pleats.
      • ‘Like the original, this shirt has an elaborate inset plastron, a half-length button band and a decorative bar tack originally used to keep the chest section buttoned tightly to the trouser waistband.’
  • 3Zoology
    The part of a tortoise's or turtle's shell forming the underside.

    • ‘The plastrons of all hatchlings were photocopied for future identification and hatchling body masses and straight-line carapace lengths were recorded.’
    • ‘This pattern, like the pattern of the dermal bones and the pattern of the scutes and bones of the plastron (ventral shell) is remarkably consistent across all turtles, particularly extant forms.’
    • ‘In addition, the carapace and plastron of each turtle were photographed.’
    • ‘No tortoise had sufficient wear to the carapace or plastron to obscure annuli.’
    • ‘Counter-shading of the shell conceals the turtle from predators, making it difficult to distinguish the dark carapace from the sea floor and the light plastron from the lighter sky.’
    1. 3.1 A ventral plate similar to a plastron in some invertebrate animals.
      • ‘To date, more than 20 specimens of D. australis have been collected at this locality, all within galleries and with dislocated plastrons.’
      • ‘For example, the plastron is a feature involved in important evolutionary changes during the early spatangoid history and underlies a distinct pattern of disparity.’
      • ‘Also, most specimens are molts, based on thickness of the carapace and posterior displacement of the sternal plastron.’
    2. 3.2Entomology (in an aquatic insect) a patch of cuticle covered with hairs that retain a thin layer of air, acting like a gill for breathing under water.
      • ‘Insects living here can usually rely on gills, plastrons, or cuticular respiration to meet their metabolic demand for oxygen.’
      • ‘This bubble is then ‘caught’ by the antennae, causing the air it contains to spread through the plastron to reach the spiracles, or breathing holes, on the beetle's abdomen.’
      • ‘Its underside is covered with a dense layer of very fine, silky hairs that trap air contained in the cocoon to form a thin, silvery cushion, called a plastron.’


Early 16th century: from French, from Italian piastrone, augmentative of piastra ‘breastplate’, from Latin emplastrum ‘a plaster’ (see plaster).