twin

n.

1. 孪生儿之一, 双胞胎之一
   • Many people thought they were twins.
     许多人以为他们是双胞胎。
2. 两个相像[密切关联]的人[物]之一
   • There are twin holes on each side of the instrument.
     这工具的两边各有一对孔眼。