Social Security officials said yesterday they plan to expand the definition of what constitutes having AIDS, a move that will increase the number of people eligible for automatic disability benefits.

David Rust, Social Security associate commissioner for disability, said the new definition will match guidelines adopted earlier this year by the Centers for Disease Control.

Rust said officials are not sure how many more individuals will qualify for the disability benefits after the broader definition goes into effect Sept. 1. So far, about 14,000 individuals with acquired immune deficiency syndrome have qualified for Social Security or supplemental Social Security Income (SSI) disability benefits.

Rust said that under the old definition, a person was not presumed to qualify for either Social Security or SSI disability benefits unless he or she had signs of both the AIDS virus and either an "opportunistic" infection (such as pneumonia) or cancer.

Now a person will also qualify if there is either dementia or wasting syndrome present with the AIDS virus. Previously, either combination was considered AIDS-related complex, which did not qualify a person for benefits.

The SSI program is designed for low-income people who are disabled and need welfare assistance, and Rust said the new definitions will have an immediate impact on people with incomes low enough to qualify them for this program.

He said a special regulation in the SSI program allows quick determinations of whether a person has the disease and grants a person three months of immediate benefits while further examinations are conducted to confirm the diagnosis.

Rust said the new definition will also be used for the Social Security disability insurance program, but because of various procedural requirements, such as a statutory five-month waiting period, benefits will not be received as quickly as under the SSI program's special three-month benefit regulation.

In June the Social Security Administration said it did not plan to use the new CDC definition. But Rust said last night that after clarification of what the new CDC definition covers, Social Security will use the new definition to determine who qualifies more or less automatically for the benefits.