遡 - go upstream, retrace the past

to go upstream; to go up (a river)

going upstream; sailing against the current

redemption; recourse

non-retroactivity

going to the source; tracing to the origin

retroactive

retroactive law; retrospective law

retrospective bibliography

retroactivity; retroaction; being retroactive (to)

going upstream; swimming upstream

right of recourse; right for redemption

anadromous fish (fish that migrates upstream, e.g. salmon)