fort vs fort up

fort is a noun but fort up is not a noun.

Word	Noun	Adjective	Verb	Adverb
fort	Yes	No	Yes	No
fort up	No	No	Yes	No

As verbs, fort and fort up are synonyms defined as:

fort and fort up: gather in, or as if in, a fort, as for protection or defense

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

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