aggravation  rule.Workers’  compensation.  The  principle  that  when  an  on-the-job  injury

combines with a preex-isting injury, resulting in a  greater disability than  that  which  would  have

resulted from the on-the-job injury alone, the entire disability is compensable as if it had occurred

at  work.  [Cases:  Workers’   Compensation     552–566.  C.J.S.  Workmen’s  Compensation  §§

325–337.] [Blacks Law 8th]