Ms. Michaels, shown here in the 1960s, died June 22 at 78. (Garbis Photo Studio)

“Ms.”

To Sheila Michaels, it looked like a typographical error when she saw the strange honorific, neither “Miss” for the unmarried nor “Mrs.” for the wed, on a Trotskyist mailing to her New York City roommate in the early 1960s.

But it was not a typo, and the honorific had existed at least since the turn of the 20th century, although it enjoyed only limited circulation.

In 1901, a writer for a newspaper in Springfield, Mass., proposed “Ms.” to guard against missteps, noting that “to call a maiden Mrs. is only a shade worse than to insult a matron with the inferior title Miss.”

The term had a certain utility in business correspondence, when the marital status of a female addressee was unknown. Some early feminists found it appealing, a counterpart to the masculine “Mr.” that did not betray one’s private life.

When Ms. Michaels saw the word, she was in her early 20s and active in the civil rights and women’s movements. Immediately she saw the egalitarian potential of those three characters. By the time of her death on June 22 at 78, she was widely credited with spurring society to make room for “Ms.” — in common English usage, in the standardized forms of officialdom and in cultural attitudes toward women.

Ms. Michaels died at a hospital in New York. The cause was acute leukemia, said a second cousin, Howard Nathanson.

The word “Ms.” was perhaps first introduced to a wide audience with the founding of Ms. magazine by Gloria Steinem and other feminist organizers in 1971. The title was proposed to Steinem by a friend who had reportedly heard Ms. Michaels promoting the term on “Womankind,” a feminist radio show in New York.

Ms. Michaels envisioned widespread use of “Ms.,” but it also served a concern of hers in particular.

“Partly because of my personal situation, partly because of my observations at large, I had a low opinion of marriage — and certainly no desire to marry,” she once told the Japan Times in an interview. “I felt strongly about not ‘belonging’ to a man — either to my father as a Miss, or to a husband as a Mrs.”

“ ‘Ms.’ ”, she said, “is me!”

Sheila Babs Michaels was born in St. Louis on May 8, 1939. Her mother was a radio writer, according to accounts of her life, and her biological father was a civil liberties lawyer. Her parents were not married, and she had several stepfathers, the result being a fluidity in her surname, the New York Times reported in an obituary.

She told the Japan Times that, during her upbringing in St. Louis, she “developed a curiosity about a woman known as Miz Noble who lived behind our house.”

“I wondered whether this meant she was unmarried or a widow,” Ms. Michaels said. “I liked the ambiguity.”

Ms. Michaels enrolled at the College of William & Mary in Williamsburg, Va., where, her cousin recalled her saying, she was kicked out because administrators considered her a “troublemaker” and didn’t agree with her “views.”

She became deeply involved with the civil rights movement, working with the Student Nonviolent Coordinating Committee and Congress of Racial Equality in the South. For periods, she earned a livelihood as a cabdriver. Later in life, she interviewed civil rights activists for oral histories housed at Columbia University.

She expressed frustration at the slow pace with which Ms. was adopted, even among her most socially minded contemporaries, although it did eventually blossom into wide use.

“No one wanted to hear about it,” she once told the London Guardian. “There was no feminist movement in 1961, and so no one to listen. I couldn’t just go ahead and call myself Ms. without spending every hour of every day explaining myself and being laughed at, to boot. I had to learn to be brave.”

Her cousin described her as “a background person” in the social movements for which she worked, a person for whom “the cause was more important than the acclaim.” But “I think it would have been nice if she had been recognized when she was alive,” he added.

Ms. Michaels’s marriage to Hikaru Shiki, with whom she operated a Japanese restaurant in New York, ended in divorce. Survivors include a half brother.

Ms. Michaels’s cousin said that, in the 1980s, she developed an intense interest in religious studies. For two decades, she gave presentations at academic conferences, with a particular focus on women in the Bible.

The Book of Ruth — recounting the Moabite Ruth’s fidelity to her Hebrew mother-in-law, Naomi, amid famine and deprivation — was among the topics Ms. Michaels found most captivating. Some feminist theologians cite it as an example of women banding together for survival.