retrospective
adjective /ˌretrəˈspektɪv/
  /ˌretrəˈspektɪv/
- thinking about or connected with something that happened in the past
- She felt a pang of retrospective sympathy for Mel.
 
 - (also less frequent, formal retroactive)(of a new law or decision) intended to take effect from a particular date in the past rather than from the present date
- retrospective legislation
 - retrospective pay awards