Some conditions and medicines weaken or impair the immune system.

This chronic condition can, over a long period of time, weaken blood vessel walls.

The ballast can be dumped overboard when conditions weaken.

The storm became a Category 2 hurricane, though unfavorable conditions weakened it back.

However, unfavorable conditions weakened the storm back to a tropical depression on September 19.

As the two parties moved south, conditions worsened and the men's physical condition weakened.

Throughout the two organizations, employee morale had eroded as the financial condition of the industry weakened.

Some conditions and medications can weaken the immune system and set off reactivation of the virus that causes shingles.

Growing competition from companies in Europe and Asia forced him to resign in 1979, when the company's condition weakened.

Unfavorable conditions weakened it, and it dissipated over the northern Atlantic ocean on the 16th.