Wiktionary
n. 1 A slender metal rod used to support or reinforce part of a structure 2 Either of a pair of rods that link the steering mechanism to the front wheel or axle of some vehicles
WordNet
n. either of two rods that link the steering gear to the front wheels
Wikipedia
A tie rod is a slender structural unit used as a tie and (in most applications) capable of carrying tensile loads only.
Usage examples of "tie rod".
My mother was six months pregnant with me and my dad was taking her to see the doctor in town when a tie rod on his truck let go and they went into the ditch.
His car had suffered a broken tie rod and veered to the right at great speed, striking an oak tree, whereupon it exploded into flames.
The brakes had burned out halfway down the slope and the steering tie rod was bent and hanging by a thread.