My conscious awareness of the meaning of the word “stepparent” didn’t begin until I married a man with three adult children. For someone is not a stepparent unless they are legally married to a person who has offspring from a prior relationship. I really should have known this, or at least given it some serious thought, because my mother was the stepmother to my father’s daughter from his previous marriage, a girl who therefore legally also became my half-sister because we had the same father.