gallantry vs courageousness

gallantry and courageousness both are nouns.

Word	Noun	Adjective	Verb	Adverb
gallantry	Yes	No	No	No
courageousness	Yes	No	No	No

As nouns, courageousness is a hypernym of gallantry; that is, courageousness is a word with a broader meaning than gallantry:

gallantry: the qualities of a hero or heroine; exceptional or heroic courage when facing danger (especially in battle)
courageousness: a quality of spirit that enables you to face danger or pain without showing fear

Other hypernyms of gallantry include braveness, bravery, courage.

gallantry (noun)	courageousness (noun)
polite attentiveness to women	a quality of spirit that enables you to face danger or pain without showing fear
the qualities of a hero or heroine; exceptional or heroic courage when facing danger (especially in battle)
courtesy towards women