acquaintance

She was a casual acquaintance of my family in Vienna..她是我们家在维也纳的一个交情不深的朋友。

He heard about the job through a mutual acquaintance (= someone you and another person both know ) ..他是通过一个双方都认识的人知道有这份工作的。

acquaintance with,相识

acquaintance with someone,对某人的相识，熟

nodding acquaintance,相识不深的人；不完整或肤浅的知识

make the acquaintance of,vt. 和…相识，结识