This is the definition of junkyard dog, a term that fits Markus Golden on a football field: a very mean and combative person willing to use any means necessary in defense of something.

Here is James Bettcher reminiscing about Golden from their four years together with the Cardinals:

“He’d walk around with a note pad, note cards … he is by-any-means-necessary-get-the-job-done guy,” Bettcher told The Post. “And I can relate to that kind of a person, ’cause that’s probably who I am.

“That’s why we gave him the nickname Junkyard Dog when he was in AZ. Because he just flew around, ran into things, second effort … that’s just what his game is about.

“If you were gonna say, ‘What is the identity of like a football player?’ I’d start writing about him.”

The kid from the mean streets of South St. Louis who realized his NFL dream and has overcome a torn ACL in 2017 to become a feared pass rusher once again for Bettcher and the Giants.

“Back in the day when I played in Arizona, they were grading the college film, and Larry Foote, he coached there, he played for the Steelers, he started calling me Junkyard Dog watching my film,” Golden told The Post. “And after that, Coach Bruce Arians, he just made it short and started calling me Junk. It went from Junkyard Dog to J.Y.D. to just Junk. I like the name, man. It describes me well.”

How so?

“Just how I play the game, man,” Golden said. “Every play 100 percent, laying it on the line and trying to do whatever I can do to help the team win.”

Golden recorded 12.5 sacks in 2016 and already has five in 2019. He is 6-foot-2 and 260 pounds of relentlessness and indomitable will at outside linebacker.

“I’m gonna come every play,” Golden said. “Every play I’m coming at you. I don’t care who you are, I don’t care about what your name is, none of that. If we’re on the football field and it’s time to go, I’m coming at you.”

He told Bettcher his mission is to be better than he was before the knee injury two years ago.

“I’m not worrying about my leg,” Golden said. “I gotta keep going. I gotta keep going. I wouldn’t say I’m all the way back. At the end of the year, I watch every play I played in. So right now, it’s just too early for me to say I’m all the way back. I feel healthy, I can say that. But I just want to keep going.”

Kyler Murray beware: Markus Golden keeps going and going and going.

“I always wanted to play in the NFL,” Golden said. “And my dream of playing in the NFL was to get here and dominate, not just be another guy playing around. I always wanted to get here and dominate. Then you get here, you gotta keep driving yourself. Then after that, my drive comes from wanting to help my team win. And that’s what I’m about, that’s the No. 1 important thing to me, ’cause if you win, everything’s good, you know?”

Golden was a running back who admired Marshall Faulk and rushed for 2,284 yards and 30 touchdowns as a senior at Affton (Mo.) High School, as well as a middle linebacker who was drawn to London Fletcher and, of course, Ray Lewis.

“My dad was telling me, ‘I think you need to hit people instead of getting hit,’ so I had to listen to my dad once it was time to go off to college [Hutchinson CC, University of Missouri],” Golden said.

Golden is excited about facing his 2015 NFL Draft classmate, Cardinals left tackle D.J. Humphries.

“Me and him had some crazy battles, tough battles, back and forth. Some days we were about to fight each other,” Golden said, laughing.

The trash talk will be flying on Golden’s way to Murray.

“He reminds me a little bit of Russell Wilson, but he’s probably a little quicker,” Golden said of the No. 1-overall pick. “He’s like a running back back there playing quarterback.”

Bettcher is a main reason why Golden signed a one-year, $3.75 million deal with the Giants.

“JB, that’s my guy, man, it’s like we’re family, family forever, I’d do anything for him, and I know he’ll do the same for me. I got a lot of love for him, a lot of respect,” Golden said.

Bettcher downplayed any emotion over playing his former team and mentioned the fond memories in Arizona. It doesn’t mean he doesn’t want bragging rights.

“Me and him feel the same way,” Golden said, and smiled. “We want to get out there and win. You always want to beat the old guys that you used to play with, or the old team you used to play with.”

Junkyard Dog, razing Arizona.