tie rod vs rod

tie rod and rod both are nouns.

Word	Noun	Adjective	Verb	Adverb
tie rod	Yes	No	No	No
rod	Yes	No	No	No

As nouns, rod is a hypernym of tie rod; that is, rod is a word with a broader meaning than tie rod:

tie rod (noun)	rod (noun)
either of two rods that link the steering gear to the front wheels	any rod-shaped bacterium
	a long thin implement made of metal or wood
	a gangster's pistol
	a visual receptor cell that is sensitive to dim light
	a linear measure of 16.5 feet
	a square rod of land