Jean E. Sammet, an early software engineer and a designer of COBOL, a programming language that brought computing into the business mainstream, died on May 20 in Maryland. She was 89.

She lived in a retirement community in Silver Spring and died at a nearby hospital after a brief illness, said Elizabeth Conlisk, a spokeswoman for Mount Holyoke College in Massachusetts, where Ms. Sammet had earned her undergraduate degree and later endowed a professorship in computer science.

The programming language Ms. Sammet helped bring to life is now more than a half-century old, but billions of lines of COBOL code still run on the mainframe computers that underpin the work of corporations and government agencies around the world.

Ms. Sammet was a graduate student in mathematics when she first encountered a computer in 1949 at the University of Illinois at Urbana-Champaign. She wasn’t impressed.