Condominium is a fighting word in Cambridge--say it in mixed company, tenants and bankers, for instance, and an argument is guaranteed.

Frustrated by the controls imposed on rents nearly a decade ago, city landlords began wholesale conversion of their apartments into high-priced luxury condos three years ago. This year, Cambridge officials, frightened by the prospect of a radically different Cambridge, with fewer working class and ethnic residents, began to fight back.

City Councilor David Sullivan drafted the legislation that has become the cornerstone of the fight--passed by the city council last August, it requires developers to obtain permits from the rent control board before converting their units.

A Middlesex Court last month upheld the ordinance in its first legal test, despite the objections of city developers who said the law represented a "confiscation of property." Further legal battles are expected, but for now the law is doing just what its proponents had hoped--dramatically slowing the rate of condo conversion.

A study released this winter by Design School students showed just how high the stakes are in the condo battle. An examination of every apartment building in Cambridge showed, the students reported, that half of all rental units would be condominium units by 1990 without government intervention. Half of current tenants would not be able to purchase their converted apartments.

The rental housing still on the market in Cambridge gets more expensive every year as well. The city's rent control board allowed large-scale rent hikes this year, and more increases are expected over the summer.

Some in the city blame Harvard and MIT for much of the housing squeeze, pointing to the universities' insatiable hunger for land and continuing expansion. Nearly 58 per cent of all property in the city is tax-exempt, and the tally grows larger every year, a report released by city officials a month ago shows.

Indeed, City Hall was draped with purple bunting per order of the City Council--in mourning over "the slow death of Cambridge from university expansion."

But the universities are only one of the enemies Cambridge confronts--the faceless specter of "economic forces" haunts this city.