Meanings
From junkyard and dog. Non-literal sense popularized by the 1973 Jim Croce song "Bad, Bad Leroy Brown" (see citation below).
How to pronounce "junkyard dog":
AU
An aggressive dog which guards a scrapyard or junkyard.
An animal or person with an especially nasty and combative demeanor.
A hot dog laden with toppings, such as onions, pineapples, or chili.
Example Sentences
1
Don't let Karen's kind face fool you, she's a junkyard dog when it comes to negotiations.
2
He may be small, but he's as fierce as a junkyard dog.
3
The new security guard at the bank is a real junkyard dog, nothing gets past him.
4
My grandma used to say she was as mean as a junkyard dog.
5
The boxer was known for his aggressive style, fighting like a junkyard dog.