A “windmill” slam dunk in basketball is when a player’s arm acts like a windmill in sending the ball through the basket. “Windmill” dunk has been cited in print since at least 1968, when it described dunks by Gus Johnson (1938-1987).
New York-area NBA players such as Connie Hawkins, Julius Erving, Darryl Dawkins, Vince Carter and Gerald Green have had famous “windmill” dunks.
Wikipedia: Slam dunk
A Slam dunk is a type of basketball shot that is performed when a player jumps in the air and manually powers the ball downward through the basket with one or both hands over the rim. This is considered a normal field goal attempt; if successful it is worth two points. The term “slam dunk” was coined by Los Angeles Lakers announcer Chick Hearn. Prior to that, it was known as a dunk shot.
Vince Carter dunked while leaping over 7-foot-2 (2.18 m) French center Frédéric Weis in the 2000 Summer Olympics. The French media dubbed it “le dunk de la mort” — “the dunk of death.” Carter is also known for introducing the “Honey Dip” or the “cookie jar” dunk in the 2000 Slam Dunk Contest, where Carter demonstrated it hooking his forearm/elbow into the rim after dunking and hanging. The “Honey Dip” at the time was unnamed. Carter used it as his speciality dunks along with his reverse 360 windmill dunk and between-the-legs dunk. When performed, much of the audience was speechless, including the judges, because none had seen these types of dunks before (although, Carter’s 360 windmill dunk is closely reminiscent of Kenny Walker’s winning “Tomahawk” dunk in 1989 except that he was going against the grain which requires more hops).
7 November 1968, The Daily Times (Salisbury, MD), “Most Exciting Team In Town, Says Gene Shue” by Gordon Beard (Associated Press Sports Writer), pg. 32, col. 3:
The only thing missing was a leaping windmill dunk shot by Gus (Honeycomb) Johnson, who sometimes scores points and shatters glass backboards at the same time.
Google News Archive
10 December 1971, The Evening News (Newburgh, NY), “Rookie Wins Game,” pg. 11B, col. 6:
It was Erving (Julius Erving—ed.) who had sent the game into overtime with a sensational windmill dunk shot with a minute left in regulation that tied it at 104.
Foul! The Connie Hawkins Story
By Dave Wolf
New York, NY: Warner Paperback Library
Connie would leap toward the basket, the ball raised above his head in one hand, then hang in the air — as though suspended by invisible wires — until, with a sudden windmill sweep, he slammed it through the hoop.
29 October 1977, Oregonian (Portland, OR), “Steele ignites rally, burns Sixers, 98-94” by Bob Robinson, pg. D1, col. 3:
The 6-foot-11 1/2 Dawkins looked much improved over last season and drew awes with a trio of windmill dunk shots.
Green’s dunk brings down the house
March, 11, 2012 12:18 AM ET
By Mike Mazzeo
Did. You. See. G.G.?!
If not, you must.
Because with 2:49 remaining in the third quarter of Saturday night’s 112-106 loss to the Rockets, Nets small forward Gerald Green brought the house down, defying the laws of gravity, cocking the ball back and nearly hitting his head on the rim before finishing off an emphatic how-the-heck-did-he-do-that? windmill alley-oop dunk from shooting guard MarShon Brooks that had the entire building buzzing.
“I’ve seen a lot of dunks in my career—and that was special,” Nets coach Avery Johnson said.