Two years ago, the alumnae association of Philadelphia High School for Girls paid tribute to Dorothy Kapenstein, a 1946 graduate who became the guardian of the illustrious school’s 171-year history.

“Every alumna knows (or should know) the indefatigable dynamo known as Dorothy Kapenstein,” read the article written by 1974 alum Marcia L. Hinton. “Ask her a question about an alum, and she will fire machine-gun accurate statistics. Don’t be deceived by her diminutive size; she is a giant within.”

Mrs. Kapenstein, 90, a retired Philadelphia teacher and librarian, died Tuesday, Oct. 15, of heart failure at Paul’s Run retirement community in Northeast Philadelphia.

“Bubbe was an absolute inspiration,” said her granddaughter Sarah Maiellano, using the Yiddish word for grandmother. “She was a feminist before that word existed. This little Jewish lady was funny, whip smart, and completely with it. At age 90, she was still researching articles and emailing regularly.”

Mrs. Kapenstein grew up in North Philadelphia in a lower-middle-class Jewish immigrant family. At Girls’ High, her boundless intellect was nurtured, and she was introduced to the classics by women with Ph.D.s.

“They couldn’t get hired at universities, so they taught us,” Mrs. Kapenstein told Inquirer columnist Daniel Rubin, who wrote about her in 2012.

She won a full scholarship to the University of Pennsylvania, where she earned a degree in ancient and medieval history and Oriental studies in 1950, did graduate studies in Middle Eastern languages, and worked in the library. She also earned a master’s degree in library science from Drexel University in 1953 and did additional graduate studies at Bryn Mawr College and what is now University of the Arts.

In 1953, she married Henry Kapenstein, deputy director of the Free Library of Philadelphia.

“Both of my parents were educated, scholarly people,” said their son Jack Kapenstein, a retired corporate accounting manager. “They dragged me and my brothers to museums. We did music, art, all kinds of advanced classes.”

Mrs. Kapenstein had a particular gift for languages.

“She spoke five languages fluently, and she could get by in four others,” her son said. “Even in the last couple of weeks, she had a conversation with a doctor in Arabic.”

In 1957, Mrs. Kapenstein began a long career in Philadelphia public schools, starting as a substitute teacher. She served as a teacher and librarian in elementary, middle, and high schools, retiring in 1991.

Girls’ High, however, was always her pride and joy. She was a board member of the alumnae association, cofounded the school’s hall of fame, and established a collection of books written by alums. She lauded her distinguished sisters, including the twins who worked as human computers in ballistics research, an Inuit language expert, the CEO of Harlem’s Apollo theater, and the chair of the investigation of the infamous Tuskegee syphilis study.

Late in life, Mrs. Kapenstein also became an entertainer. It started when she cracked jokes while discussing the sociology of Jewish humor in her grandson’s class at Penn, and continued with gigs at senior centers. She carried a business card that said, “Bubbe, the world’s oldest standup/sit down comedian.”

Besides her son and granddaughter, Mrs. Kapenstein is survived by her sons Larry and Joe, her brother Mitch Goldstein, nine grandchildren, and five great-grandchildren.

Services were Friday, Oct. 19.