a person you do not know
A stranger asked me for directions on the street.
Children are taught not to talk to strangers.
✦ From Old French estrangeor, from estrange (“foreign, unknown”).
someone who is not familiar with a place, group, or situation
Being a stranger in a new city can be exciting and scary.
As a stranger to their customs, he watched politely.
✦ Extension of the basic meaning 'unknown person' to include unfamiliarity with environments or experiences.