1. two children or animals born at the same time to the same mother
2. two things that are very similar or identical

Examples

• The twins were born just minutes apart.
• She has identical twins who look exactly alike.
• The twin boys are in the same grade at school.
• These twin towers were built at the same time.
• The twin beds in the guest room are very comfortable.
• My twin sister and I share many interests.
• The twin engines on the boat provide extra power.