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

"I loved her to bits, she was my big sister who did everything for all of us."

From BBC

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

I couldn’t bear the thought of anything bad happening to my big sister.

From Literature

More like a second mother than a big sister.

From Literature

In this week’s episode of The Envelope podcast, the “Sentimental Value” star reflects on growing up onscreen and following in big sister Dakota Fanning’s footsteps.

From Los Angeles Times