The term "perfect stranger" refers to someone who is completely unknown to us. However, there are several other words that can be used to express the same idea. Some of the synonyms for the word "perfect stranger" may include unfamiliar person, unacquainted individual, unknown person, anonymous individual, and alien person. Each of these phrases has a slightly different connotation, but they all relate to someone who we do not know personally. Other possible synonyms for "perfect stranger" might include outsider, newcomer, or complete stranger. These words can all be useful in different contexts, depending on the specific meaning that we are trying to convey.