big sister

American  

noun

1. an elder sister.

2. (sometimes initial capital letters) a woman who individually or as a member of an organized group undertakes to sponsor or assist a girl in need of help or guidance.

3. (sometimes initial capital letters) a young woman in the junior or senior class in college who advises a young woman in the freshman class on studies, social activities, etc., often as a part of a sorority program.

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Example Sentences

What she found was that the relationship went beyond business; she sees her agent as part negotiator, part therapist, part big sister.

From The Wall Street Journal • Mar. 4, 2026

She paid tribute to Sakamoto who is affectionately called "big sister" by her teammates.

From Barron's • Feb. 20, 2026

When Calvin’s big sister Evelyn would come home from college at Loyola Marymount University, they’d play board games for hours.

From Los Angeles Times • Dec. 17, 2025

Lotte is like my big sister, or more like my mum.

From BBC • Sep. 20, 2025

Plus, I'm a good big sister, so it's probably the same kind of thing.

From "Betty Before X" by Ilyasah Shabazz and Renée Watson