A Bronx teacher says her language lesson was lost in translation when she was fired for calling a student “Negro” — though she claims she was simply using the Spanish word for the color “black” at the time, according to a new lawsuit.

The non-tenured junior high instructor, Petrona Smith, 65, was booted from the bilingual PS 211 in March 2012 after a seventh-grader reported the alleged insult.

Smith, who is black and a native of the West Indies, has been unemployed since her ouster.

“They haven’t even accounted for how absurd it is for someone who’s black to be using a racial slur to a student,” said Shaun Reid, Smith’s attorney. “Talk about context! There’s a lot of things wrong here.”

The instructor took a hiatus from teaching special education in 2005 to learn Spanish in South America, because she was passionate about learning the language in a cultural context, Reid said.

Smith was also accused of calling her students “failures.”

But in court papers she claims that second insult was also a misinterpretation.

Smith had allegedly asked students who had failed a test to move to the back of the room, but says she never called them failures.

She denied calling the student a “Negro,” and explained to investigators that she was teaching a lesson about how to say different colors in Spanish and said the word “negro,” which is Spanish for the color black. She told her students that it was not a derogatory term and that the Spanish word for a black person was “moreno.”

She added that she’d been verbally abused by her charges, including being called a “f—ing monkey,” a “cockroach” and a “n—r,” but had never stooped to their level.

A 2011 investigation substantiated the student’s undated claims based on accounts from four seventh-grade witnesses, even though the student’s own parents said he’d lied about the event.

A spokeswoman for the city Law Department said, “We have received the papers and will review them.”