friend of a friend

Noun

An acquaintance known vaguely through a mutual friend; someone that one does not know well.

Japanese Meaning

共通の友人を通じて知り合ったあいまいな知人、あまりよく知らない人。

I accepted the invitation because the host was a friend of a friend and seemed trustworthy.

主催者が友人の紹介で知り合った人で、信頼できそうだったので招待を受けました。

Sense（1）

An acquaintance known vaguely through a mutual friend; someone that one does not know well.

friends of friends

（ plural ）