“约”: three functions

“约”

1. (N.)
   
• transliteration of foreign language / e.g. 纽约 (New York)；里约 (Rio de Janeiro)
  
• contract; agreement / e.g. 合约；期货合约
• appointment / e.g. 我跟医生有约。
2. (V.) to make an appointment
   
• e.g. 我约医生去打球。
3. (Adv.) approximately
   
• e.g. 跟AIT去平溪的约（有）35个人。