lessen the severity of something
palliate - reduce
To ‘palliate’ is to reduce the bad effects of something without curing, eliminating, or solving it entirely. This formal word is most commonly used in medical terminology in relation to a disease or illness, but is also frequently encountered in a broader context related to lessening the extent or seriousness of something.
Unfortunately, Luke’s condition is terminal, so the drugs he has been prescribed are simply to palliate the painful symptoms of the disease.
My sick grandfather is currently receiving palliative care. It ensures that he is as comfortable as possible for what remains of his life.
Stop trying to palliate your mistake by claiming that it was a freak accident. It was, in fact, a result of ineptitude and gross negligence.