expression, noun
stranger; outsider; someone not from one's group
Refers to a person who is not a family member, friend, or part of one's immediate social circle. Often used when contrasting with 身内 (close relations) or 知り合い (acquaintances).
See also: 余所
子どもに、よその人について行ってはいけないと教えた。
I told my child not to go with strangers.
彼はよその人には冷たいが、友達には優しい。
He is cold to outsiders but kind to his friends.
他人 is a more general term for 'another person' or 'stranger', often used in legal or formal contexts. よその人 emphasizes the person as an outsider from a specific group or family.
知らない人 simply means 'a person one does not know'. よその人 carries a nuance of being from outside one's own circle, not just unknown.
Compound of よそ (elsewhere, another place) + の (possessive particle) + 人 (person). The word よそ itself is of uncertain origin, possibly related to 余所 (other place).