A stepparent is the person who married your mother or your father but is not your mother or father by birth — that is, your stepmother or your stepfather. The word is the general one that covers both, the way "parent" covers mother and father. Because of that, you hear it most in the places where the exact person does not matter: laws, school forms, newspaper articles, advice books. In real conversation people are much more likely to name the actual person — "my stepmum", "my stepdad", or very often just "my mum's husband" or even simply "my dad" if the bond is close. So if a student says "I live with my stepparent", it is correct English but sounds oddly official, like something out of a report. There is a useful pair to remember: the adult is the stepparent, and the young one is the stepchild. Two words, one relationship, seen from opposite ends. Spelling varies a little — you will see stepparent, step-parent, and step parent all in print, with the single word most common now.

繼父母（繼父或繼母的統稱）。這個字比較正式，常出現在法律、學校表格、報導裡；平常講話台灣人多半直接講「我後爸」「我後媽」或「我媽的先生」。跟 stepchild（繼子女）是同一個關係的兩端。