A while back means some time in the past.Also, a while ago. This term uses a while in the sense of "a short or moderate time," a usage dating from about 1300.
Note:
A while back意思是一段時(shí)間以前，過去的某個(gè)時(shí)間。也可以說a while ago。從1300年開始，while可以 代表并不長的一段時(shí)間。
例：I ran into Barbara a while back but didn't get her new address.
我前陣子偶然遇到Barbara，但是沒得到她的新地址。
Note:
A while back意思是一段時(shí)間以前，過去的某個(gè)時(shí)間。也可以說a while ago。從1300年開始，while可以 代表并不長的一段時(shí)間。
例：I ran into Barbara a while back but didn't get her new address.
我前陣子偶然遇到Barbara，但是沒得到她的新地址。