tie down vs truss

tie down is not a noun while truss is a noun.

Word	Noun	Adjective	Verb	Adverb
tie down	No	No	Yes	No
truss	Yes	No	Yes	No

As verbs, tie down and truss are synonyms defined as:

Other synonyms of tie down include bind, tie up.

tie down (noun)	truss (noun)
	a framework of beams (rafters, posts, struts) forming a rigid structure that supports a roof or bridge or other structure
	(medicine) a bandage consisting of a pad and belt; worn to hold a hernia in place by pressure
	(architecture) a triangular bracket of brick or stone (usually of slight extent)

tie down (verb)	truss (verb)
restrain from independence by an obligation	support structurally
secure with or as if with ropes	tie the wings and legs of a bird before cooking it
	secure with or as if with ropes