Negative for malignancy means that no cancer cells were seen when the tissue sample was examined under the microscope. Pathologists use the word malignant to describe cancers.
Your pathologist can only provide a diagnosis based on the tissue sample sent for examination. For that reason, negative for malignancy only means that no cancer cells were seen in the small sample examined. If your doctor is still concerned that a cancer may be present, they may recommend performing a second procedure to provide the pathologist with more tissue to examine under the microscope.
The opposite of negative for malignancy is positive for malignancy.