When we say "perfect strangers," we are referring to individuals who are entirely unknown to us and hold no prior connection. Several synonyms can replace this term, depending on the context. The phrase "complete stranger" suggests a person we know nothing about, while "total stranger" implies an individual we have no familiarity with at all. The term "unfamiliar face" refers to someone we have never seen before, whereas "unknown person" is someone we do not recognize or know by name. If you are looking for a slightly more formal term, "unacquainted people" can be used. No matter what word you use, they all convey the idea of meeting someone new with no prior knowledge or connection.