calm vs sang-froid

calm and sang-froid both are nouns.

Word	Noun	Adjective	Verb	Adverb
calm	Yes	Yes	Yes	No
sang-froid	Yes	No	No	No

As nouns, sang-froid is a hyponym of calm; that is, sang-froid is a word with a more specific, narrower meaning than calm:

Other hyponyms of calm include aplomb, assuredness, cool, poise, placidity, quiet, repose, serenity, tranquility, tranquillity.

calm (noun)	sang-froid (noun)
steadiness of mind under stress	great coolness and composure under strain
wind moving at less than 1 knot; 0 on the Beaufort scale

calm (adjective)	sang-froid (adjective)
(of weather) free from storm or wind
not agitated; without losing self-possession

calm (verb)	sang-froid (verb)
cause to be calm or quiet as by administering a sedative to
make steady
make calm or still
become quiet or calm, especially after a state of agitation