"The word that I hate most is 'unbelievable,'" said the man who had been tortured. He wore a well-cut, pin-striped suit, and his face, tanned the color of his expensive gold wristwatch, reflected the irony in his voice.

"What people want to hear about first is the torture. I am tired, but I try to tell them. 'Unbelievable,' they say. That's the word they used when the witnesses came out of the concentration camps.

"But I have an idea. On the television talk shows, I will agree to be tortured just as I was in Argentina. Then everyone will know what it's like.

"It would be easy, because the equipment is very simple. All you need is an electrical outlet, and a small transformer with a dial, and two wires for the electrodes. Here it's 110 volts, and in Argentina it's 220 volts, but otherwise the same. I would want a doctor in attendance.

"The first stage is pain, excruciating pain wherever the electrodes are applied. People would say my muscles contract, my hands drawing up in fists like this, my back arching, and hear that particular scream.The second stage, when they turn the dial up, destroys the tissue wherever the electrodes are applied. The testicles, say. The third stage stops the heart." He touches his chest. "I would agree to be tortured on television to the first stage."

Jacobo Timerman was on the "Today" program yesterday, and will be interviewed today by the CBS Morning News, Cable News Network and Bill Moyers. It is unlikely that American news organizations will take him up on his offer, even to the first stage.

Much better to retain a certain distance from Jacobo Timerman, the distance appropriate to the outspoken intellectual whose case has come to symbolize the Argentina Problem -- the problem of a nation struggling to govern itself while beset by terrorism, kidnaping, bombings, a 170-percent inflation rate and the scrutiny of its political allies.

Timerman, now 58, was until April 15, 1977, the publisher and editor in chief of La Opinion, a liberal daily newspaper in Buenos Aries. He was outspoken, and influential and seen frequently on Argentine television. On that date, 20 armed men entered his 15-floor luxury apartment, handcuffed him from behind, and took him to prison. He was jailed until Oct. 13, 1977, and kept under house arrest thereafter until Sept. 24, 1979. Twice the Argentine supreme court found that he was imprisoned without charge. The second time it so found, the junta responded with a threat to disband the supreme court. Timerman, however, had become a nuisance also in his incarceration. So his citizenship was revoked, his newspaper and all his possessions confiscated, and he was expelled from the country.

In ridding itself of Jacobo Timerman, the Argentine military government gave his story to the world. Bitter and combative, it now reaches out from the pages of his book, "Prisoner Without a Name, Cell Without a Number," and the spate of articles and interviews accompaning his book-promotion tour. The context of his story is Argentina, where since 1976 thousands of persons have "disappeared" -- estimates of how many range from 6,000 to 20,000 -- and many more have been arrested and imprisoned.

But it begins and ends with the Jewishness, which he requires that others confront as he has confronted it.

"To be a Jew is to have almost a second biology," he said in Washington this week. "That is what I have learned. You are a man -- and a Jew. You are a journalist -- and a Jew. The question is always of survival. Nobody can explain why anti-Semintism exists, why a people is hated. Yet we are. Before Argentina there was the Holocaust, and before the Holocaust the Inquisition. That is why I am a Zionist. We must have a homeland, and we must have guns."

Timerman was more than a Jew and a liberal. He was rich, and a Zionist. A military officer once described him as "a talented, arrogant Jew." His partner in La Opinion was David Graiver, also a Polish-born Jew. The junta believed Graiver was funneling money for the Montaneros guerrilla movement. Graiver was arrested, but later died in a plane crash.

Timerman was jailed and tortured but never charged. "That's the way it works in a totalitarian system. You're arrested because you're guilty. He was presumed guilty of participating in a worldwide plot to wreck economic havoc in Argentina -- and specifically to seize control of Patagonia and establish a Jewish state there.

"I would be taken from the torture machine into another room, and there would be a man, an intellectual, smoking a pipe, pronouncing his words correctly. A man just like you or me, who would carefully explain that he was not a torturer.

"Then he would say: 'We know Brzezinski is a Jew. We know President Carter is a Jew, he changed his name from Braunsweig. We know Brzezinski has a plan to take over Brazil and Argentina and Chile. You must tell us about the details.'"

Did they really expect answers? He shrugged. "They were enjoying themselves. They had the Jew where they wanted him, at last." The Fatalist

By birth a Jew ("I am not at all observant"), by vocation a political journalist. He served his apprenticeship on the dailies of Buenos Aries. One day, he recalled, his editor told him that the time had come when he could have a by-line. This was a great privilege because most articles were unsigned.

"'One thing,' the editor said. 'Jacobo sounds too Jewish. Why don't you sign your name as Alejandro?' But I held out, and at the time I thought I had scored a great victory. Only now I realize that it was a great defeat that the question should arise at all."

Timerman also revealed a talent for entrepreneurship. In the 1960s he introduced the newsmagazine concept to Argentina by founding the journal Primera Plana. It was unsuccessful. He sold it and used the profits to found the daily La Opinion in 1971. He was both publisher and editor in chief, with 45 percent of the stock. Gravier had 51 percent. Timerman's success was now conspicuous. He had his fine 15th-floor apartment with a view. He had a holiday home in Punta del Este, in Uruguay, "like the other rich men in Buenos Aries."

La Opinion was a liberal paper, distinctly intellectual, and it followed no predictable party line. But then, neither did Argentina. Between 1973 and 1976 there were four Peronist presidents, and a dozen notable political and military and revolutionary splinter groups, encompassing Trotskyite guerrillas, Peronist death squads, labor unions, the Church and competing branches of the armed forces. The nation was at war with itself, but the front was everywhere within its long borders reaching southward between the sea and the Andes.

One morning Timerman received two letters at La Opinion. One was from a rightist terrorist group, condemning him to death. The other was from the Trotskyite Popular Revolutionary Army, also threatening him with death.

Timerman responded on Page 1, revealing the threats and wondering with fatalistic curiosity, "Who will wind up with my corpse -- the terrorist of the left or those of the right?"

Timerman had at one point called for a coup -- the traditional method of changing governments in Argentina -- and in retribution Isabel Peron closed La Opinion for 10 days. The coup came in 1976, putting the army in power. But it was the army -- the Nazi contingent within the army, he says -- that arrested him and took him away. Heroic Measures

But the first question is always about the torture. "Unbelievable."

"People say that a strong man can come out of torture with whatever he had when he went in, but it's not true. Some parts of my spirit were destroyed." He scoffs at the notion that torture can be withstood, that torture tests and defines the hero.

"No," he said, "when you are tortured to learn the address of a building, or the name of a man, you are lost.You will tell them anything. Albert Camus gave these instructions to the French Resistance: Try to hold out long enough for the others to escape. But do not die under torture. Try to survive. Of course, Tito's Underground received different instructions: They were supposed to die. That seems unreasonable.

"Mine was an ideological torture, because I had no address they wanted. Mine was a torture only from hate. It was not only the machine, but being tied in a chair all night, intentionally wet down. Of being required to soil yourself.

"It's hard to describe. I begin to think that perhaps everyone should be tortured. Tell me what you think of this idea: When you graduate from high school, you are tortured to the first stage for five minutes. Then when you get a college diploma, you must undergo another 10 minutes. If you want to run for office, another 15. This way it would not seem unbelievable."

He is congratulated on his sense of humor.

"Oh, I have no sense of humor," he said. "Only a sense of irony." End of an Ideology?

This week in Washington, Timerman, as a spectator, visited the Senate Foreign Relations Committee hearings on President Reagan's nomination of Ernest W. Lefever to head the U.S. human rights program. Introduced by Sen. Charles H. Percy (R-Ill.), Timerman was greeted with loud applause. Lefever represents a less conspicuous policy regarding human rights in friendly governments. This is being called "quiet diplomacy," in contrast to the aggressive policies of Jimmy Carter.

"A quiet diplomacy is a silent diplomacy," Timerman was saying the next day. "Nations maintained a silent diplomacy with Hitler, and you see what happened.

"America gets impatient with human rights, restless. You don't see the accomplishment. Do you expect to change a government with a policy? No, if you want to change the government you have to send in the Marines. What a human rights foreign policy does is save lives. And Jimmy Carter's policy did. How many? I don't know. Two thousand? Is that enough? But that policy is even more important to you than to us. It builds up a democratic consciousness in the United States. It is more important for the United States that Lefever be defeated than for Argentina.

"I am very disappointed in President Reagan," he said. "A new administration is entitled to change an approach, to change a strategy, but not to change a policy. The policy of human rights belongs to United States history. This adminstration is not changing a strategy, but an ideology.

"So much in Argentina is unique," he went on. "And no one knows about it.

The murders, the disappearances, the tortures. Just to ask the names of the missing persons was extremely dangerous, and yet how could a newspaper not ask? This is why I did not go into exile, although my wife and my sons and I talked about it many times.

"My wife would say, 'I will run the paper, you escape.' I would say, 'No -- I will run the paper, you escape.' But how could we when there was a Committee of Mothers of Missing Children asking our help? Do you know that in Argentina there is also a Committee of Grandparents of Missing Children? Where else in the world would you find a Committee of Mothers of Missing Journalists?

"Think of it. More than 100 journalists have disappeared in Argentina in the past four years. How come nobody knows about that? How come the newspapers of the world have not merely printed their names? This is a genocide of journalists, and nobody knows."

Those are the things Timerman says in interviews, and to anyone who will listen. It is not possible to corroborate the statistics of Argentina chaos. But Timerman's corroboration is his experience: He was arrested, but he was never disputed with a formal charge. The Spirit in Exile

He is a survivor, of course. Although the junta confiscated all his property, including La Opinion (which he valued as well over $5 million, and which has been shut down), they could not touch his summer home in Uruguay. He sold it, and that money established him in Tel Aviv, where he lives now. His wife is there, and two of his sons. The third son is in New York, studying foreign affairs. Timerman has just written another book, about Israel, and does a column twice weekly in Maariv, and is not troubled financially. Timerman likes Israel, but he is not used to the colors. "The blue of the sea is too blue. It is not the blue of the South Atlantic."

Yet in this week of witness in America, his opinions probably wield more power than they ever have before.

He scoffs at the notion that he has survived intact, and with power.

"Part of my spirit has been destroyed," he said. "The great cost has been to my peace of mind. I try to come back now to the things that were most important to me, and I cannot. It is very frightening. I have lost the ability to read the great poets, Sophocles, or T.S. Eliot, or Delmore Schwartz, that were so important to me. I have been invited to Princeton to write a book about the effects of torture on the spirit, and I may do it. But I am afraid of what I may learn.

"You see, I was not degraded by the torture, but I was deteriorated. Many times I have asked myself, without my wife and children what would I do? Because of them, I cannot wake up in the morning and begin to suffer. iBut if it were not for them, I would always travel. I would be alone, and have no permanent things. I would keep from remembering, for that is the trick of survival under torture, and the big tragedy."

Timerman believes that Argentina must improve, that the worst times are over there, and that many of the 1 million exiles will eventually be able to return. Perhaps he will, too, because it is the land where he grew up, and made his fortune, and raised his family?

"No," he said sharply. "I will never return. I cannot. You see, I was not treated there as a political enemy, I was not hated for my politics. I was hated because I was a Jew, and I can never return to that. I will stay in Israel.I am no longer ashamed to love my Jewishness, because when I was in the disaspora, I was ashamed."