CULTURES often have multiple words for the same core concept. Just as the nomadic Somalis have 45 separate words to identify the camel because of the dromedary's importance to their lives, Mexicans employ a number of synonyms to decry the Tammany Hall-style corruption that suffuses their political system.Fraude (fraud), engano (cheating), sesgo (bias) - just a few of the invectives that opposition parties hurled at the ruling Institutional Revolutionary Party (PRI) after the Aug. 18 congressional elections. Preliminary results show that the PRI, with 61.7 percent, beat the center-right National Action Party, or PAN (19.4 percent), and the leftist-nationalist Democratic Revolutionary Party, or PRD (7.9 percent). The PRI also captured the six governorships at stake, including the top post in Guanajuato state. There Ramon Aguirre, backed by peasant and labor bosses in the PRI's anti-reform "dinosaur" wing, defeated the PAN's nominee, Vicente Fox, a squeaky-clean businessman with an exemplary record of civic achievements. Fox insists that PRI-inspired irregularities in 700 of Guanajuato's 3,853 precincts sent him down in flames. In 200 of these polling places, he says, more people voted than were registered; in another 200, Aguirre supposedly received every ballot cast. PAN officials have scorned the vaunted PRI "landslide" as a slap in the face to President Carlos Salinas de Gortari, who has pledged to convert Mexico from authoritarian rule to democracy. Is this uproar merely sour grapes by the losers? Or do PRI zealots still cook vote tallies despite Salinas's call for political modernization? Since winning a fraud-plagued election three years ago, Salinas has become Mexico's most effective chief executive in a half century. He has cracked down on venal labor bosses, jailed stock market manipulators, escalated the war against drug lords, and thrown tax cheats behind bars. Even more impressive has been the 43-year-old leader's commitment to market forces. He has slashed subsidies, privatized banks and white elephant state firms, energized the business community, and championed a free-trade accord to integrate Mexico's once-hugely protected, statist economy with those of the United States and Canada. These efforts have activated an economy that was flat as a tortilla during the 1980s. National income growth, which reached 3 percent in 1990, will approach 4.5 percent this year. Meanwhile, the continuance of a labor-business-government stability pact has reined in inflation, which had soared to triple digits. Salinas has also launched a "Solidarity" program to uplift the poverty-stricken denizens of shantytowns and rural villages who flocked to his opponent in 1988. Under this extremely popular, well-financed initiative, the government channels resources to communities willing to pony up pesos, sweat-capital, or materials for clinics, schools, and other projects they designate. While markedly hostile toward politicians in general, Mexicans admire Salinas's bold leadership. He boasts a 62 percent approval rating, according to a recent poll. Only 16 percent of Mexicans expressed a "negative" opinion of their president. Salinas's long coattails have greatly benefited his party. A month before the election, the PRI (63 percent) enjoyed an overwhelming lead over the PAN (17 percent) and the PRD (14 percent). An election-day exit survey conducted by a Gallup affiliate showed the PRI (62.7 percent) trouncing its political foes. Even as these independent polls underscore the governing party's formidable strength, several factors explain the persistent charges of hanky-panky. To begin with, crying foul is - after soccer - the favorite sport of Mexican politicos. PRI militants who lost nomination bids earlier this year screamed as loudly as the PAN and PRD activists are now doing. In addition, while the government vastly improved the nation's voter registry this year, 9.7 million of the 45.8 million voting-age population failed to obtain new voter ID cards. Electoral officials insist that they did the best job possible; the PAN and PRD claim discrimination against citizens in their political strongholds. Finally, it's tough to stop business-as-usual shenanigans at the grass roots. Doubtless, Salinas wants to clean up PRI's unsavory image, especially with the free-trade agreement being negotiated. Aguirre and party hacks, however, view modernization as the political equivalent of castor oil. They continue to treat adversaries with all of the tenderness of Cromwell ruling Ireland. Although admitting minor irregularities, one presidential spokesman praised the recent contest as "the cleanest election in Mexico ever." He may be correct - except for Guanajuato and a few other areas where the opposition has a legitimate beef. Still, observers on both sides of the Rio Grande tend to think the worst about political practices here. Salinas is right to demand that critics submit hard evidence to substantiate claims of wrongdoing. Yet only when he demonstrates - perhaps through a nonpartisan commission - that Aguirre won fairly will such words as credibilidad (credibility), legitimidad (legitimacy) and justicia (justice) grace this country's political vocabulary.