Stepchild

A stepchild is the offspring of one's spouse, but not one's own offspring, either biologically or through adoption.

Perception

The traditional use of a term "stepfamily" included to a married couple where one or both members of the couple pull in children, with a different biological parent. Some also apply the term loosely to non-custodial relationships where “stepparent" can refer to the partner of a parent with whom the child does not live.