Edwin Newman picks his words carefully. He has to. People are watching.

"If I make a mistake on television," he says, "I will certainly hear about it quickly. People who know as much about the language as I do, or more, will notice it. I suppose that's good-but sometimes I am accused of mistakes that I haven't made."

It's not easy being the Don Quixote of the save-our-language movement. Since his first book on the subject, "Strictly Speaking," hit the best-seller lists in 1974, followed by "A Civil Tongue" in 1976, Newman, 60, has become the principal standard-bearer for word-watchers.

He is currently wondering how his fans will react to his next book, a novel due out in June. "It's called 'Sunday Punch,' and it's supposed to be funny," he says. "I hope it's funny."

Funny or not, you may be sure the words will be scrupulously chosen.

The NBC news commentator came to Washington yesterday to speak on the values of plain, forceful English-in the heart of enemy territory. He was the 12th speaker in the Arthur S. Flemming/Wilbur J. Cohen Distinguished Speaker Series at the Department of Health, Education and Welfare. HEW Secretary Joseph Califano said, "When we were giving out tickets, I urged department heads to give those tickets to HEW regulation writers. I also recommend his books to HEW regulation writers."

Newman drew a standing-room audience who heard on ehorrible example after another of people being "safely rescued," work "fully completed," smallpox "successfully eradicated."

"The language has few enemies more virulent than lawyers," Newman said, as as attorney Califano smiled benignly. He brought up a new medical term for death, "terminality," and asked the rhetorical question: "O terminality, where is thy sting? He quoted a job description from an employment application and commented:

"Is the design and implementation of pragmatic interfaces' something we want to happen? I'm not sure."

Later, driving to the airport where he barely missed a shuttle to New York, Newman reflected on the curious circumstances that made him such a popular advocate.

"After Vietnam and Watergate, people began to realize that language was being used to deceive them.

"They were afraid that misuse of the English languate will in some way contribute to the decline of the country. I think they were right-a breakdown of language is more than a symptom of social breakdown. It accelerates the decline: Beauty disappears, grace and humor and subtlety disappera, pleasure declines."

The NEW lecture was one of about two dozen that Newman give annually. After 'Strictly Speaking' was published, he said, "the invitations increased 200 or 300 percent."

Newman's books hit the public at the crest of a wave of interest which had begun much earlier-with a small, dogged band of English scholars. Its most powerful expression came in George Orwell's 1946 essay, "Politics and the English Language."Newman took up the cause because "as a journalist, I had long felt that many of the stories we were handling many of the stories we were handling had little real merit, that we were dealing in slogans. In preparation for writing the book, I decided I would not read what anyone else had written on the subject. I thought I might be intimidated. On the same principle, my book make no appeals to authority."

Newman believes the decline of language has been slowed and perhaps reversed in the five years since "Strictly Speaking." "There is a lot more ridicule of pompous language than there used to be. More people are paying attention to these abuses and doing something about them.

"There is also a significant movement to simplify language in such documents as insurance contracts and bank loan applications-and this movement began before we had plain-language laws."

But there is still a long way to go, he believes, when a greeting-card store calls itself a "social expression center" and a motel room contains not a bed but a "sleep system."

One of the toughest and most securely entrenched enemies of plain English is the federal bureaucracy, Newman believes. He said that if Jimmy Carter succeeds in his campaign to simplify bureaucratic prose, "It will prove that he is a political genius.

"The idea is to make things unclear, to create a small, inviolable world behind a screen of words that the public will be unable, or afraid, or too bored to penetrate," he explained.

"Words are used to give overtones of profundity where there is none, to impress the gullible and to make the ordinary seem more considerable than it is. Scientific terms are taken from a field where they may be appropriate, and applied where they are inappropriate-to give a false scientific air to unscientific utterances. We may expect to see the word 'meltdown' being used in this way.

"It is also curious that people, when they reach a certain status, feel that a certain kind of language is required of them. When he is 'addressing' a problem-which is what we do now-[a cabinet member] feels that he cannot use plain language."

Newman is aware that the problem he has been discussing is actually two problems. Pretentious prose is vulnerable to his weapon of ridicule; but ht efact that many young Americans are leaving school without having acquired a basic, working command of the English language is not.

"It isn't right to make fun of people in that situation," he said, "because many of them are in it through no fault of their own."

It is a long way from such ponderous concerns to his new book, "Sunday Punch," which will tell the story of a fight manager, Fogbound Franklin, and a wispy, but tough British fighter, Aubrey Philpott-Grimes, who is a championship contender and a student of economics.

There was a slight hint of what might have been relief in Newman's voice when he said, "My publisher will want me to give a lot of talks when this book comes out. But I'll be talking about a new subject." CAPTION: Picture, Edwin Newman; by Doug Chevalier-The Washington Post