Stepmother is your father's wife who is otherwise not related to you. Your father divorced or was widowed and got remarried. His new wife is your stepmother. Mother in Law is your husband's/wife's mother :)

Stepmother is the woman who is married to someone's father. Mother in law is the mother of someone's husband or wife.

stepmother is your father's wife but not your birth mother mother-in-law is your wife's mother

Exactly so! The information provided so far is all correct! Thumbs up for ''Amene'' as well as ''Poppy Amelia Sevina'' for taking the time to thoroughly explain. : ) Well, I'd like just to add that that is true for all the 'in-law's'. In other words - in English, the term 'in-law' is transferred to the relation or correlation of all the supposed members of one's spouse's family. GLOSSARY - spouse: formal term used when referring to someone's husband or wife. In case of any question or doubt regarding this comment, please, feel free to leave me a message. Hope I've been a bit of a help. : )

exemple: your father marry with a woman, she is your stepmother, and if she allready had a daugther/son she will be ur stepsister/stepbrother...Your mother-in-law is the mother of your wife and you can also call mother-in-law mumy of ur girlfriend, and her dad is your stepfather