WASHINGTON — Bill Walsh, a Washington Post copy editor who wrote three irreverent books about his craft, noting evolutions and devolutions of language, the indispensability of hyphens, and his hostility toward semicolons, and distinctions — for the sake of clarity — between Playboy playmates and Playboy bunnies, died March 15 at a hospice center in Arlington, Va. He was 55.

The cause was complications from bile-duct cancer, said his wife, Jacqueline Dupree.

In the hurly-burly of a newsroom, where even the best reporters have widely varying degrees of grammatical competence, copy editors are the often unheralded guardians of language and common sense. They are the front-line mud soldiers in an endless war against bad spelling, ill-considered sentence construction, and factual errors.

They prevent English teachers everywhere from wincing. They save behinds.

By many accounts, Mr. Walsh stood at the zenith of his profession.

Mary Norris, a recently retired New Yorker magazine copy editor and author of ‘‘Between You & Me: Confessions of a Comma Queen,’’ called Mr. Walsh ‘‘that rare thing: a celebrity copy editor . . . clever, decisive, entertaining, and knowledgeable, in person and on the page.

‘‘Generous and collegial,’’ she continued in an e-mail, he was ‘‘sought-after on the copy-editing circuit (and there is one!).’’

The publication American Journalism Review once described Mr. Walsh as ‘‘the undisputed king of copy bloggers.’’ He dubbed his long-running editing and grammar website The Slot, after the nickname for the central location the copy chief traditionally occupied in the newsroom. In the era before computers, rank-and-file copy editors sat along the edge, or ‘‘rim,’’ of the copy desk, tossing headlines and stories to the slot in the center.

Among other positions during his 20 years at The Post, Mr. Walsh served as the copy chief of the national and business sections.

Mr. Walsh wrote three volumes about copy editing, ‘‘Lapsing Into a Comma’’ (2000); ‘‘The Elephants of Style’’ (2004), which punned off William Strunk Jr. and E.B. White’s ubiquitous grammar handbook ‘‘The Elements of Style’’; and ‘‘Yes, I Could Care Less: How to Be a Language Snob Without Being a Jerk’’ (2013).

Mr. Walsh relished playing the part of a curmudgeon, writing from the perspective of ‘‘some past-his-prime newspaper guy . . . yelling at you.’’

While holding his ground on proper word choice, capitalization, and subject-verb agreement, Mr. Walsh was far less prescriptive than other language mavens regarding split infinitives, conjunctions at the beginning of a sentence, and prepositions at the end.

A copy editor must at all times exercise vigilance in word choice, he said. A Playboy bunny is a Playboy Club waitress who has donned a cottontail uniform, he explained, while a playmate is a centerfold.