The Celtics’ word for the day is “correctable.”

Yeah, the Celtics went with “correctable” over “photosynthesis.” It’s easier to spell and besides, correctable mistakes have far more bearing on the first round Eastern Conference playoff series with the Knicks anyway.

So while the Metro New York area sang the praises of the Knicks defense in Game 1, the Celtics reverted to cussing themselves out for items such as a ghastly array of turnovers, poor decisions and getting smashed on the offensive glass. And much of the misery, the Celtics feel, was self imposed.

“We gave up 10 offensive rebounds but I think it was the timing of them that really killed us,” said Paul Pierce, referring to the Knicks grabbing four offensive boards — as many as the Celtics had all game — in the first 4:41 of the fourth quarter and two of those by Raymond Felton. “But the biggest thing I’m looking at is the turnovers. I mean 20 turnovers in a playoff game, that just can’t happen.”

It didn’t. There were 21 turnovers.

“We made bad decisions,” Boston coach Doc Rivers said yesterday at the team’s Midtown hotel — ironically, the Celtics and Bulls are at the same hotel and both lost Saturday. “This was a quiet, dark hotel last night. The New York host teams didn’t treat their guests very well.”

The Celtics hope to reverse that decision-making trend tomorrow night. But first they were seeking to correct all that went wrong.

“A lot of it, we just became impatient. Three or four post passes to Kevin [Garnett] were just impatience, instead of just advancing the pass,” Rivers said. “They saw Kevin and wanted to get it to him so bad. One of them was a cross-court post pass which I don’t think I’ve ever seen, and the other was a pass from beyond halfcourt to the post. Those are passes we can’t make. But that’s why the film is good. They’ll see that.”