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.

---

Example Sentences

The pregnancy had been far enough along to start getting their 4-year-old daughter excited about decorating a nursery, family-of-four camping trips and what it would mean to become a big sister.

From Salon • May 27, 2026

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

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 • Feb. 26, 2026

Affectionately called "big sister" by her teammates, she is leading a new generation of Japanese stars including Nakai, 17, and Chiba, 20.

From Barron's • Feb. 17, 2026

My big sister is not good at this whole game, even though she’s spent a year away at college.

From "Pride" by Ibi Zoboi