Noun

1. Armor for the body, as, the body breastplate and backpiece taken together.
2. Also used for the entire suit of the day, including breastplate and backpiece, tasset and headpiece.
   • 1786, Francis Grose, A Treatise on Ancient Armour and Weapons, page 21:

     Strictly speaking, the word corcelet meant only that part which covered the body, but was generally used to express the whole suit, under the terms of a corselet furnished, or complete.

3. A type of women's underwear, combining a bra and a girdle in one garment.
4. The thorax of an insect.