-trən noun
( -s )
Etymology: Middle French, from Old Italian piastrone, aug. of piastra thin metal plate — more at piaster
1.
a. : a metal breastplate worn under the hauberk
b. : a quilted pad worn during fencing practice to protect the chest, waist, and side on which the weapon is held
2.
a.
(1) : the ventral part of the shell of a tortoise or turtle consisting typically of nine symmetrically placed bones overlaid by horny plates
(2) : the ventral armor of other animals (as some extinct amphibians or glyptodonts)
b. : the modified posterior interambulacral area on the under side of a heart urchin
c. : the ventral plate of the cephalothorax of a spider — compare sternum
3. : a separate or attached front for a garment usually extending from neck to waist:
a. : a trimming like a bib for a woman's dress
b. : dickey 1 b
4. : a thin film of air held by hydrofuge hairs of certain aquatic insects