Teamsters Union President Roy Lee Williams said today that he knew what a bribe was and swore that he never conspired to offer one to Sen. Howard W. Cannon (D-Nev.), no matter what FBI tape recordings suggest.

Taking the stand in federal court, the square-jawed Teamsters chief began his testimony in calm, confident tones, but became pugnacious on cross-examination, frequently interrupting the prosecutor and claiming a complete lack of memory about damaging conversations in which Williams had taken part.

The only "commitment" he ever made to Cannon, Williams insisted, was "a fair shot at purchasing" a piece of Teamsters Central States Pension Fund property in Las Vegas that the senator and his neighbors wanted to buy in early 1979.

On that score, "I certainly gave my word," Williams testified. "If your word's no good, you're no good," he said. But he denied going any further, as the government has charged, and promising to deliver the property to the senator at a below-market price in return for Cannon's help in blocking trucking deregulation legislation.

At one point, with jurors in another room, chief prosecutor Douglas Roller accused Williams of an "incredible lack of recollection" and replayed several government tape recordings. On one, Williams could be heard saying that "we set right there and committed ourselves" to Cannon on Jan. 10, 1979, and that the "bastards" impeding the transaction were "not gonna treat us this way."

Williams also said during the same conversation that he was trying to find out "what in the hell was wrong" with the sales effort " 'cause I got whistled in by the senator . . . to find out what was wrong."

Asked about those remarks, Williams denied being "whistled in" by Cannon about anything and said he had no idea why he made the statement.

Roller also questioned Williams closely about a talk that Williams said he had with Allen Dorfman April 23, 1979, about the Las Vegas property and the Cannon group's attempts to buy it.

Roller suggested that Williams and Dorfman, a millionaire insurance executive long associated with the Teamsters, might have been in the Kansas City home of a trucking company official named Phil Simone on that date.

Williams said that he did not know where Simone's house was and that he was certainly not there April 23, 1979. But, after a recess, he said he might have been there after all.

According to a 1981 report by the Senate permanent subcommittee on investigations, law enforcement sources indicated that Williams and Dorfman met with reputed Kansas City crime boss Nick Civella at Simone's home on the date in question.

The subcommittee said the purpose of such meetings "was to fashion a strategy for enabling crime syndicate bosses like Civella in Kansas City . . . to reassert their influence upon the Central States Pension Fund."

Williams exercised his rights under the Fifth Amendment when questioned more than two years ago by the Senate subcommittee about his reported attendance.

Questioned about the crucial Jan. 10, 1979, meeting with Cannon, Williams testified that he attended only reluctantly to discuss deregulation problems bothering the Teamsters, at the request of then-Teamsters president Frank Fitzsimmons.

Williams said that at the end of the meeting in Cannon's inner office, which Dorfman had arranged, Cannon told Dorfman, "Allen, I believe I will make a bid on that property." According to Williams, Dorfman replied, "Gee, that's great. We'll do everything we can to see that Palmieri the company in charge of pension fund assets deals fairly with you."

Williams said he did not know what they were talking about until, after leaving Cannon's office, he asked Dorfman "what this deal was about." Williams said Dorfman told him about the property and in turn, "I asked Allen if the senator was willing to pay top dollar.

"Allen said, 'Absolutely,' and I told Allen, 'Fine, then we should do all we can to help him purchase it, to see to it that he got a fair deal in buying the property,' " Williams testified.