shut in vs swallow

shut in is not a noun while swallow is a noun.

Word	Noun	Adjective	Verb	Adverb
shut in	No	No	Yes	No
swallow	Yes	No	Yes	No

As verbs, swallow is a hyponym of shut in; that is, swallow is a word with a more specific, narrower meaning than shut in:

shut in (noun)	swallow (noun)
	the act of swallowing
	small long-winged songbird noted for swift graceful flight and the regularity of its migrations
	a small amount of liquid food

shut in (verb)	swallow (verb)
surround completely	believe or accept without questioning or challenge
	keep from expressing
	tolerate or accommodate oneself to
	take back what one has said
	utter unclearly
	engulf and destroy
	pass through the esophagus as part of eating or drinking
	enclose or envelop completely, as if by swallowing