na-adjective, noun which may take the genitive case particle 'no', noun
Describes a person of exceptional courage and strength, often in a literary or slightly formal context. Can be used as a noun or adjectivally with な or の.
彼は剛勇の士として知られている。
He is known as a man of bravery.
その武将の剛勇な戦いぶりは語り草になっている。
The commander's valiant fighting style has become legendary.
Compound of 剛 (firm, strong) and 勇 (brave). The exact historical derivation is uncertain, but the combination has been used to describe martial valor.