1. a female who has the same parents as another person
2. a female member of a religious community
3. a woman who shares a bond or common purpose with another
Usage: informal

Examples

• My sister is two years older than me.
• She has three brothers and one sister.
• Sister Mary teaches at the local school.
• The sisters at the convent pray every morning.
• We’re like sisters even though we’re not related.
• Sister Johnson is in charge of the hospital ward.
• My sister and I share the same bedroom.