One word spoke volumes about a man who could talk for days. It was a slip of the tongue that came after a game in late November. The word was quickly clarified, but one small pronoun left a lasting impression.

“It’s still early in the season. I’m not expecting this team to play the type of defense that they did when we won it — when they won it. Excuse me,” he said.

Just two months into his first season with the Celtics, Rasheed Wallace was all in.

“It’s not even about adopting the ‘Celticsness.’ It’s about adopting the teamness issue,” he told WEEI.com. “You can’t divide the locker room. I know there’s a couple of new guys here, but once we got here we couldn’t divide it to the point where it’s like, ‘Oh, well, they’re playing good right now, we’re running the team.’ No, it’s a whole team issue.”

The Celtics are Wallace’s fifth team in his 14-year career. He played nearly eight seasons with the Trail Blazers and more than five seasons with the Pistons. Yet the word “we” rolled off his tongue like he had been playing in Boston since he was a rookie.

“I’ve still got [my Pistons jerseys] at the crib. That didn’t change, because that’s still part of what I did,” Wallace said. “But I still have them at the house, still have some of my Portland stuff. It’s tucked away. I don’t do all that wall stuff, that’s my wife. But with me, I don’t care about all that. It’s just something that’s just tucked away.”

Yet, Wallace — as a Piston — was involved in a heated series with the Celtics during the 2008 Eastern Conference finals, famously denouncing the C’s home court advantage and guaranteeing victories against them. With such hostility once directed at the Celtics, you might think the C's would have a hard time coming to grips with Wallace’s defiant attitude and loud nature.

“If he’s on another team he’s supposed to think like that,” Kendrick Perkins said. “But now that he’s on our team, he doesn’t think we’re supposed to lose.”

But what about his liberal use of the term “we”? Is it too soon? Coach Doc Rivers has a different take.

“We want everyone to talk in ‘we's,’ ” Rivers said. “We even tell them that, ‘When you reference championships, say we.’ You’re a Celtic, and once you’re a Celtic, you’re always a Celtic.”

Wallace, 35, came to the Celtics with the same mindset as his new teammates. They have a small window of opportunity to win with a veteran group, and time is of the essence. According to Wallace, it is the ideal situation for a former title-winner hungry to lift the trophy one more time.

“It’s definitely a good career move, because I have the chance to get that ring on the way out,” he said. “Not too many people can say that. You’ve got most veterans who go to a team where either they barely make the playoffs or they’re not even in contention. So it’s great to come to a team that a lot of people are saying could possibly win the championship.”

He added: “I think everyone that plays this game or comes to the NBA, before their career’s over, they definitely want to get a championship so you can be immortalized. That’s pretty much how I see it. All the other personal accolades to me are nothing. But once you get that championship, you could be the 15th man on there, but guess what? You’re going to be immortalized, because you’re going to be set in stone.”

With the same goal in mind, the Celtics and Wallace just clicked, his teammates say. His transition to the C’s felt seamless for both Wallace and those around him.

“He got here and he fit into our system right away,” Brian Scalabrine said. “He’s a perfect guy for what we’re trying to do. Defensively, he can guard centers and power forwards. He’s smart, he talks on defense, and he can shoot the basketball, we can go to him in the post. He’s just a perfect fit for us on this team. We were very fortunate to get him last year.”

Ray Allen believed so strongly in Wallace’s fit that he joined Paul Pierce, Kevin Garnett, Rivers, president of basketball operations Danny Ainge and co-owner Wyc Grousbeck for a visit to Wallace’s home in Michigan over the summer. Even though the trip was only in July, Allen feels like Wallace has been in Boston for years.

“Now it just feels like he’s always been here. He just falls in,” he said. “He’s got a personality, he’s got years of tenure, and he’s never said it himself like, ‘This is the way we’re going to do things.’ He just fits right in. We all adjust to each other and it makes us a team.”

Not all of the Celtics were initially as certain as Allen. Perkins had faced off against Wallace several times throughout his career and admittedly was not sure what to expect from his former foe. His opinion quickly changed.

“Sheed is a great guy. He’s a great team player,” Perkins said. “He’s better than what I expected as far as team-wise, the communication in the locker room, how much of a team player he is. He’s all about the team and none about himself. I think he’s got the right mindset that he’s coming in with.”

Wallace’s winning attitude was both appreciated and trusted. When he went through an offensive slump and shot 3-for-24 from 3-point range and 12-for-41 from the field during a five-game stretch in November, his teammates stood by him. “Oh, [I have] a lot of confidence. What’s being [said] about him?” Marquis Daniels said at the time, seemingly unfazed by the struggles.

Even as Wallace shot his way out of the slump (he is averaging 11.4 points off of 43.2 percent field goal shooting over the last five games), his basketball IQ never wavered. Not only is Wallace a quick learner, according to his teammates, but he already came to Boston with an anthology of Xs and Os he had accumulated during his career. Scalabrine points to Wallace’s movement without the ball on the pick and roll as an example.

“It’s just one of those things where we didn’t have to tell him that and coaches don’t even mention it,” Scalabrine said. “But it’s exactly the perfect place you want to be for him to be able to make a play. It goes well for his strengths, which is his playmaking ability and he’s a guy who can shoot.”

But someone as colorful and animated as Wallace has to bring more than just skills to a new team. This season, the Celtics' chemistry has been strengthened, not divided, by his larger-than-life personality. It is not unusual to see him add his own commentary to his teammates’ interviews or tease them for their preference in football teams. (He makes his passion for the Kansas City Chiefs well known, especially to those who root for the Chiefs’ opponents.)

“The first day I realized it, how he socialized with everybody, his approach,” Perkins said. “He was loud and joking around. He was saying what his role is, ‘My role is to come in, give a few hard fouls, and shoot some 3's.’ That’s what he was saying, so I think he’s the perfect fit for our team.”

Paul Pierce has seen a lot of players come and go through the Celtics locker room. When asked if he has ever had a teammate with quite as much character, he put Wallace in rare company.

“He’s an extension of Kevin [Garnett],” Pierce said with a laugh. “Between the two, you hear a lot of stories. It’s fun. I could write a 400-page book right now.”

 And the title of the book?

“I’d keep it simple: ‘Kevin and Sheed’ ... [The cover would] probably have them two face to face, smiling,” Pierce said.

Even though Wallace does plenty of talking on the court, it turns out he is just as vocal behind the scenes. His musical prowess, if you will, already has made an impression on his teammates. In fact, it was the first thing Allen pointed to when offering what people should know about Wallace off the court.

“He thinks he can sing, everything,” Allen divulged, smiling. “He thinks he can sing everything.”

“Sheed can break out Phil Collins. He can go from The Eagles all the way to new stuff like Pearl Jam and Akon, so he’s pretty versed,” Scalabrine explained. “I would say that with him, the biggest thing is confidence and he believes in himself when it comes to singing. Confidence is probably the most important thing you can have. It shows on the court as well as the karaoke.”

Whether he is setting a screen to get his teammates open or busting out a tune to make them laugh, Wallace’s team-first attitude has been a valuable addition to the C’s this season.

After years of playing against them, he took no time to embrace the Celtics organization. It is a franchise built on the concept of “we,” one word that the man of many words finds effortless to personify.

“Yeah, it’s just what I do, period,” Wallace said, “Because we’re all in this together, we’re all playing for the same cause, the same purpose. So it’d be hard, like I said, to try to individualize the whole effort.”