From Longman Dictionary of Contemporary Englishstepsisterstep‧sis‧ter /ˈstepsɪstə $ -ər/ noun [countable] SSFFAMILYthe daughter of your stepmother or stepfather
Examples from the Corpus
stepsister• A daughter, shunned by her stepmother and stepsisters, managed to make it to the ball with the help of magic.• Another aspect which holds large appeal for the child is the vileness of the stepmother and stepsisters.• The prince and the eldest stepsister rode away together.• My stepmum has two daughters and my stepdad has three, so I've now got five stepsisters.• She had never even referred to herself as his stepsister before!• If he thought she was going to be a nice little stepsister he could think again!• My sly little stepsister Katie calls me Andy Pandy.• Cinderella, which tell how the stepsisters mutilated their feet to make them fit the slipper. 