step-parentnoun [ C ]
mainly UK also mainly UK step parent, US usually stepparent uk/ˈstepˌpeə.rənt//ˈstepˌper.ənt/a parent who is married to the father or mother of a child, but who is not that child's own father or mother; a stepfather or stepmother:
We offer confidential advice to step-parents on creating good relationships with their teenage stepchildren.