say-so vs muscle

say-so and muscle both are nouns.

Word	Noun	Adjective	Verb	Adverb
say-so	Yes	No	No	No
muscle	Yes	No	Yes	No

As nouns, muscle is a hyponym of say-so; that is, muscle is a word with a more specific, narrower meaning than say-so:

say-so: the power or right to give orders or make decisions
muscle: authority or power or force (especially when used in a coercive way)

Other hyponyms of say-so include power of appointment, carte blanche, command, imperium, lordship, sovereignty.

say-so (noun)	muscle (noun)
the power or right to give orders or make decisions	possessing muscular strength
an authoritative declaration	authority or power or force (especially when used in a coercive way)
one chap's arbitrary assertion	one of the contractile organs of the body
	animal tissue consisting predominantly of contractile cells
	a bully employed as a thug or bodyguard

say-so (verb)	muscle (verb)
	make one's way by force