I don't know him—he's a perfect stranger.

我不认识他，他是百分之百的陌生人。

《牛津词典》

Perhaps a perfect stranger.

或许是完全的陌生人。

youdao

If it were a perfect stranger in your position, what would you think?

如果一个陌生人身处你的境况，你会作何感想？

youdao

And then should it surprise us that that's the kind of person who would call a perfect stranger on the telephone and write a sexy story and give it to them? Right?

我们是否应该感到吃惊呢,正是这类人会为给一个陌生人打电话,并为对方写一个性感小故事？

耶鲁公开课 - 心理学导论课程节选

It's a sad, sad story when a mother will teach her daughter that she ought to hate a perfect stranger.

NPR: 'Nice' Reward: Five Grammies for Dixie Chicks

Every day, Dietzel goes to work and, at some point, has to hand a gun to a perfect stranger who has never used one.

NEWYORKER: Battleground America