George Weinberg, a psychotherapist, author of the 1972 book “Society and the Healthy Homosexual,” and a highly acclaimed straight ally in the LGBT rights movement, died March 20 in Manhattan of cancer. He was 87.

Weinberg, who held a doctorate degree in clinical psychology from Columbia University, has been credited with playing a key role in changing public attitudes about homosexuality and gay people by debunking prevailing views in the 1960s and 1970s that homosexuality was a mental illness.

“He coined the word ‘homophobia’ in his 1972 book, ‘Society and the Healthy Homosexual,’ to propose that those who harbor prejudice against gay people and not gay people themselves are suffering from a psychological malady, an irrational state of mind,” an official biography posted on his website says.

In the book he says one of his longstanding goals as a psychotherapist was to help homosexuals as well as non-homosexuals overcome homophobia.

“This has entailed helping homosexuals in our phobic society to accept themselves and to regard their own homosexual desires as valid,” he wrote. “The premise is that in a truly great society there is room for all who do not infringe on the rights of others.”

Activists who knew Weinberg said he joined forces with early gay rights leaders Frank Kameny, Barbara Gittings and Jack Nichols, among others, who launched a campaign in the 1970s to persuade the American Psychiatric Association to remove homosexuality from its official list of mental illnesses.

The campaign succeeded, opening the way for a dramatic shift in public opinion and in the portrayal of gay people in the mass media, activists like Kameny said at the time.

Weinberg is the author of 13 books on mental health related issues as well as mathematics and English literature, subjects he called dear to his heart. He appeared regularly in the 1970s and 1980s on national television talk shows, where he often spoke in support of LGBT rights.

He also wrote about his views on homophobia and what he called misleading and false assumptions about gay people held by many of his colleagues in the mental health profession in popular magazines such as Cosmopolitan, Glamour and TV Guide.

“George Weinberg was an early straight ally to the LGBT community who is responsible for introducing the concept of ‘homophobia’ into everyday language and thought,” said Jack Drescher, a clinical professor of psychiatry at New York Medical Center who’s considered an expert in sexual orientation and gender identity matters.

“His was no small accomplishment, as the concept shifted society’s focus away from an automatic hatred or disdain for gay people and instead asked what’s wrong with people who feel that way,” Drescher said. “Instead of gay people having to explain themselves, the haters did — or as is often the case, they had to publicly and falsely deny they were haters.”

A native of New York City, Weinberg received his undergraduate degree from the City College of New York and a master’s degree in English literature from New York University prior to receiving his doctorate at Columbia University.

He spent most of his career as a practicing psychotherapist in New York City. He is survived by his wife, Dianne Rowe.