means People you don't know — individuals with whom you have no acquaintance, connection, or familiarity.

from From the Old French 'estrangier,' meaning a foreigner or someone from outside, which traces back to the Latin 'extraneus' — literally 'that which is on the outside,' from 'extra,' meaning 'outside.' The same Latin root gives us 'strange' and 'extraneous,' which makes a quiet kind of sense: a stranger was simply the person standing beyond your circle, outside the warm room of the known.