Definition of plastrons:
(n) :
(zoology) The nearly flat part of the shell structure of a tortoise or other animal, similar in composition to the carapace.
(n) :
(fencing) A half-jacket worn under the jacket for padding or for safety.
(n) :
A breastplate.
(n) :
A man's shirt-bosom.
(n) :
An ornamental front panel on a woman's bodice.
(n) :
A film of air trapped by specialized hairs against the body of an aquatic insect, and which acts as an external gill.