knitting vs tie up

knitting is a noun but tie up is not a noun.

Word	Noun	Adjective	Verb	Adverb
knitting	Yes	No	No	No
tie up	No	No	Yes	No

knitting (noun)	tie up (noun)
creating knitted wear
needlework created by interlacing yarn in a series of connected loops using straight eyeless needles or by machine

knitting (verb)	tie up (verb)
	secure with or as if with ropes
	finish the last row
	restrain from moving or operating normally
	secure in or as if in a berth or dock
	invest so as to make unavailable for other purposes