fort vs shut in

fort is a noun but shut in is not a noun.

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

As verbs, shut in is a hypernym of fort; that is, shut in is a word with a broader meaning than fort:

Other hypernyms of fort include close in, enclose, inclose.

fort (noun)	shut in (noun)
a fortified defensive structure
a fortified military post where troops are stationed

fort (verb)	shut in (verb)
station (troops) in a fort	surround completely
enclose by or as if by a fortification
gather in, or as if in, a fort, as for protection or defense