Saviour (noun)
alternative spelling of savior|from=British|from2=Canadian
Savior (noun)
A person who saves someone, rescues another from harm.
Savior (noun)
A child who is born to provide an organ or cell transplant to a sibling who has an otherwise fatal disease used in combination, with “sibling”, “baby”, “child”, “brother”, “sister”, etc.
Wiktionary