Definition - What does Stepparent mean?
A stepparent is a person who becomes the parent of a child through marriage. So, for example, a woman who marries a man who has a son would become a stepparent to the man's son upon marrying the man.
In the context of the law, stepparents are not official legal guardians of their stepchildren unless they formally adopt them.
Justipedia explains Stepparent
Stepparents are very common in America. The reason is because many marriages end in divorce, and after a divorce, many people remarry. So, people who remarry after having kids often have their new spouse become the stepparent to their kids.
Both mothers and fathers can be stepparents. Because stepparents are not automatically legal guardians, they cannot do things like sign legal contracts on behalf of their stepchildren unless they formally adopt them.