The Collaborative International Dictionary
Lug \Lug\ (l[u^]g), n. [Sw. lugg the forelock.]
The ear, or its lobe. [Scot. & Prov. Eng.]
That which projects like an ear, esp. that by which anything is supported, carried, or grasped, or to which a support is fastened; an ear; as, the lugs of a kettle; the lugs of a founder's flask; the lug (handle) of a jug.
(Mach.) A projecting piece to which anything, as a rod, is attached, or against which anything, as a wedge or key, bears, or through which a bolt passes, etc.
(Harness) The leather loop or ear by which a shaft is held up.
(Zo["o]l.) The lugworm.
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A man; sometimes implying clumsiness. [slang]
Lug bolt (Mach.), a bolt terminating in a long, flat extension which takes the place of a head; a strap bolt.
Lug nut (Mach.), a large nut fitting a heavy bolt; -- used especially of the nuts used to attach wheels to vehicles.
Lug wrench (Mach.), a wrench used to tighten or loosen lug nuts, usually a steel rod having a hexagonally shaped socket which fits closely over the lug nut; sometimes in the shape of a cross, having several such sockets, one at the end of each arm, to accommodate nuts of different sizes.
Wiktionary
n. A strong nut used to attach a wheel to an axle of a motor car.
Wikipedia
Usage examples of "lug nut".
He wiped his eyes, and then briefly tightened each lug nut in turn.
She came to the first hydrant and tried to twist the huge painted lug nut on the side.
Burke was a chunky man, strong, dark-complected, balding, tough as a lug nut.
As he struggled with a tight lug nut, the wrench slipped and he skinned one knuckle.
Apparently feeling at a disadvantage, he stood again and went to lean on the mantel, soothing himself with swallows of booze and strokes down the rustic back of a saber-toothed cat, its body made from an oversized spring, a lug nut for a head.
I bypassed the office and went straight to the service bay, where a cursing mechanic was struggling to loosen a stubborn lug nut on a flat tire.
Back at the entrance ramp about thirty minutes later, Earl Van Diver tightened the last lug nut and released the air from the inflatable jack.