Definitions

1. noun

a piece of armor that covers the chest and upper abdomen, typically made of leather or metal

“The knight wore a breastplate over his chain mail for added protection.”

2. noun

a badge or emblem worn on the chest, especially as a symbol of office or achievement

“The mayor wore a breastplate with the city’s coat of arms on it.”

3. noun

the front or upper part of something

“The breastplate of the wave crashed against the shore.”