old girl  
noun uk/ˌəʊld ˈɡɜːl/ us/ˌoʊld ˈɡɝːl/
  (OLD WOMAN)         
  [ C ] mainly UK informal老妇人,老太婆 
an old woman
  The poor old girl doesn't get out much these days. 那可怜的老妇人如今不常出门了。 
  [ as form of address ] mainly UK old-fashioned informal(用于男性称呼相知多年的女性朋友)老朋友,老伙伴,老姐姐 
a way that some men address female friends that they have known for many years
  Come on, old girl, we haven't got all day. 快点,老姐姐,我们可没多少时间。 
   (STUDENT)      
 [ C ] UK女校友 
An old girl of a particular school is a woman who went to school there as a child.
  an old-girl reunion 女校友聚会