GREEN BAY, Wis. — The “Hail Mary” is, by definition, a prayer. It is taught to young Catholic children as part of a nightly bedtime ritual. Specifically, this prayer asks for help — for the intercession on the praying individual’s behalf by a celestial figure believed to have the ear of the highest of higher powers.

“Hail Mary” wasn’t a football term until 1975, when Dallas Cowboys quarterback and former Catholic school kid Roger Staubach hit Drew Pearson for a 50-yard game winner in the playoffs against the Minnesota Vikings. Asked about the play after the game, Staubach explained that he was knocked down as he threw and had no idea what was happening. “I just closed my eyes,” he said, “and said a Hail Mary.”

For Aaron Rodgers, the Hail Mary at this point is more play than prayer. He has executed three of them now, in NFL games, in the span of about 13 months. Two have come in playoff games. The biggest happened Sunday, just before halftime of the Green Bay Packers38-13 wild-card victory over the New York Giants. Rodgers rolled to his right, gave his receivers time to get into the end zone and then heaved a steep, 64-yard parabola into the back of the end zone, where Randall Cobb caught it, kept his toes in bounds and put six impossible points on the scoreboard.

The effect it had on the game and respective seasons of those two teams was total.

“It felt amazing,” Rodgers said later. “It felt like it was meant to be today.”

The effect on the score was obvious. The Giants, who had reason to feel as if they’d dominated the Packers throughout the first half, were suddenly down 14-6 at halftime. For a team that averaged 19.4 points per game in its otherwise impressive 11-5 regular season, this was no small problem. The mere math of it all was discouraging enough.

But over in the Green Bay locker room, they knew it was more than that.

“I know what it’s like on the opposite side of that, because I remember when they did it to us,” Packers tackle Bryan Bulaga said.

Five years ago, in that very same end zone in this very same stadium, with time expiring in the first half, Giants quarterback Eli Manning hit Hakeem Nicks with a Hail Mary that turned a 13-10 game into a 20-10 game and helped propel the Giants to an upset of a 15-1 Packers team and, a few weeks later, a Super Bowl title.

When Bulaga went back to the field after halftime Sunday, he said, he sat on the bench and watched Giants players filing back out for the second half. He thought about how deflated they must have felt.

“It definitely takes the wind out of your sails,” he said. “The energy just leaves you. I’ll never forget it.”

The flip side, though, is a 12-minute buzz that sizzles through the other team’s locker room, where they can’t wait to get back on the field.

“It was calm in here, but you know how it is when you look a man in the eye and he’s ready to go kill?” Packers tight end Jared Cook asked, to a reporter who (fortunately) had to tell him no. “It’s a quiet storm, let’s put it that way. It was a quiet storm in here.”

It didn’t stay quiet. The Packers outscored the Giants 24-7 the rest of the way. Playing without his favorite receiver (Jordy Nelson, who left the game with a rib injury in the first half), Rodgers sliced up one of the NFL’s best defenses. He was 14-for-18 passing for 207 yards and two touchdowns in the second half — 25-for-40 for 362 and four touchdowns for the game. The Packers had 105 yards of offense before the Hail Mary, 42 on the play itself, and 259 after it. The Giants cut the lead to one point, briefly, in the third quarter. But even then, you got the sense that Rodgers was rolling and wouldn’t lose this one. The Hail Mary opened the floodgates, and not even the Giants’ vaunted defense could stop the flood.

“As much as you want to pretend it doesn’t matter, that’s huge,” Giants receiver Odell Beckham Jr. said. “That’s tough, and you can kind of feel it.”

The Packers practice the Hail Mary every week, but Rodgers says he hasn’t thrown one in practice since Week 4 or 5. That’s because the drill is a defensive one in which the aim is to make sure no one executes the Hail Mary against them. The Packers are just as liable to use backup Brett Hundley to throw the practice Hail Mary as they are to use Rodgers, who has clearly practiced it enough.

“I mean, it’s like a perfect ball,” Bulaga said. “I’d love to see the Sports Science of how it actually goes. He throws it so high, and the way it descends, I think, gives the receiver a real chance to catch it. But I think it also makes guys misjudge it.”

Rodgers throws the Hail Mary basically straight up in the air, on a steep angle so it seems to drop straight out of the sky. This is no coincidence. He has drilled this, and clearly believes it helps the ball’s chances of being caught.

“The high arc is definitely by design,” Rodgers said. “I want to make sure those guys get a chance to get down there and jump. The key is the offensive line giving you a little bit of time. So we just did a little roll to the right, and obviously backside was firm in the protection. By the time I get to the spot on the field where I want to throw it, I’m 100 percent confident that the ball is going to be in a catchable spot. It’s just a matter of those guys getting in the right situation, and that’s how you draw it up. Obviously, you don’t think you’re going to catch it every time, but we’ve been fairly successful with it.”

Bulaga was way back up near the 42-yard line, where the play originated, and with the mass of humanity in the end zone blocking his view, he looked instead at the big video board atop that end of Lambeau Field.

“And there’s Randall, just waiting back there to catch it,” he said. “Amazing.”

Cobb wasn’t supposed to catch the ball. He said his job on that play is to “box out, give our jumper a little bit of space to jump.” The jumper is supposed to be Davante Adams, who was positioned in the middle of the end zone where the defenders were concentrated. Rodgers thought, as Bulaga did, that most of his receivers and the Giants’ defenders misjudged the ball’s descent.

“I guess everybody but me,” Cobb said.

The Hail Mary is calamity, which means there’s contact all over the place as receivers try to catch the ball and defenders try to knock it down. Cameras showed Cobb shoving a Giants defender in the back to create a little space in the back of the end zone, but offensive pass interference isn’t likely to be called on a play as chaotic as the Hail Mary.

“Just a little bit. Not too much,” a smiling Cobb said of his push-off. “They didn’t throw the flag, so …”

So, touchdown, and momentum, and the Packers head to Dallas next week for an epic-looking divisional-round matchup while the Giants’ season ends. Yeah, there was another half of football to play. And yes, technically, the Giants still had a shot.

But there were players on each team who could remember what it felt like to be in a halftime locker room on the other end of that play, and somewhere deep inside they knew what every good Catholic school kid knows: After you say your Hail Mary, the next words you usually hear are “good night.”