connection/ kə'nεkʃən /

1.noun [c/u] 
(link) 联系

2.noun [c] [电子] 
接头

3.noun [c] 
(train,plane etc) 联运

4.noun [c] [电信] 
(for caller,new subscriber) 接通

5.n pl
connections (people) 熟人

what is the connection between them?
他们之间有什么关系?
to have a connection with {or} to sb/sth
与某人/某物有联系
in connection with
与…有关
to miss/get one's connection
误了/赶上要换的交通工具