If you wish to see editors come to attention around a newsroom, let them hear the word "plagiarism." Webster defines this contemptible business as using "without due credit the ideas, expressions or (artistic) productions of another." For a time last week, this prospect threatened to rob The Washington Post of any holiday cheer. Indeed, the only surcease from the generally dismal news everywhere was the idea of Christmas.

That's why the paper was pleased on Christmas Eve to have run "A Christmas Story," an evocative account by Associated Press writer Hugh Mulligan of the circumstances that impelled Charles Dickens to write his owm immortal "A Christmas Carol." Page two of The Post was all dressed up with art of Dickens, Scrooge, Tiny Tim and Bob Cratchit.

The issue was barely a day old when some crabby letter writers took The Post to task for aiding and abetting plagiarism. Mr. Mulligan's piece, they argued, was nothing more than a steal from a similar story published some weeks earlier in an Alexandria, Va., magazine by one Henry N. Ferguson. The magazine, The Retired Officer, described Mr. Ferguson as "a frequent contributor . . . a free-lance writer residing in Kerrville, Texas." The letters excerpted passages to demonstrate identical language. One example:

Mr. Mulligan: "Like Scrooge, he (Dickens) was capable of the extremes of benevolence and malevolence. A soft touch for pan-handlers, especially down-at-the-heels actors, he kept a close eye on family budgets and made scenes over hotel bills."

Mr. Ferguson: "As was Scrooge, Dickens was capable of the extremes of benevolence and malevolence. He was a soft touch for panhandlers, especially out-of-work actors. Paradoxically, he kept a close rein on the family budget and argued vociferously over hotel bills."

You get the idea.

"The comparisons could continue ad nauseam," one writer said, noting elsewhere, "it appears that The Post, which prides itself on being a bastion of integrity in the news media, has been had again."

Another suggested that "it was Mulligan who wrote with scissors and paste pot."

Well, it turns out that Mr. Ferguson plagiarized Mr. Mulligan, not the other way around. Worse, we now learn it happened at least once before.

The chronicle of this literary larcency is fascinating: Mr. Mulligan wrote "A Christmas Story" 25 years ago. The AP's feature service offered it to client newspapers initially in December 1957. It was run, according to AP, by hundreds of papers that year (and by many as a reprise since). Four years later, on Dec. 24, 1961, the old New York Herald Tribune published in its book review pages a near word- for-word text of Mr. Mulligan's story under Mr. Ferguson's by-line. Obviously taking it seriously, the editors commissioned the famous British caricaturist Ronald Searle to illustrate it, while describing Mr. Ferguson as "long a student of the life and hard times of Charles Dickens."

On seeing it, the AP challenged the newspaper, which, after being shown Mr. Mulligan's text and date of origin, acknowledged it had been duped. The issue was dropped, however, mainly because the Herald Tribune went out of business a short time later.

Commenting good-naturedly on all this a few days ago, Mr. Mulligan said: "Back then, he (Ferguson) was even more greedy for my words. He used almost every one of them word for word. I feel like I have been mugged twice by the same assailant with my own Boy Scout knife. And at Christmas, too."

Reached at his home, Mr. Ferguson, who is 73, would say little more than the subject "is a mystery to me." He claimed he had never seen Mr. Mulligan's original story, saying twice he did not recall being published in the Herald Tribune. "Maybe," he allowed, "someone gave me some information one time." He said he would be responding to a letter of inquiry from the editor of The Retired Officer, but would give no indication of what he intended to say by way of explanation. Asked several times to explain the coincidence between the article of 1961 and this one 20 years later, Mr. Ferguson would say only, "I don't know how this could happen."

The letter writer who raised the image of Mr. Mulligan with "scissors and paste pot" is a teacher of English at a senior high school in Maryland. She had quoted extensively from Mr. Ferguson's version to her classes on the day before the Christmas recess. "It was a fearful shock," she said, "to read the one in The Post two days later. As a teacher I have tried to emphasize the seriousness of plagiarism to my students and the severity with which it will be dealt if detected."

She is unequivocally right. If there is one misdeed that warrants the stigma of unredeemability, it is plagiarism. She is now aware that her censure of Mr. Mulligan and The Post was misdirected. Writing in reply to the teacher, Executive Editor Ben Bradlee urged that students be told "there is no greater sin for a writer than to steal from the works of others. The result is the opposite of truth."

What motivated Mr. Ferguson in this and the earlier episode is impossible to know. If it weren't a serious matter, it would unavoidably recall the "Grinch" who, while stealing the Christmas tree, said: "I'm taking it home to my workshop, my dear. I'll fix it up there. Then, I'll bring it back here."

For the nonce, hats off to Hugh Mulligan.