The word 'foreign' is secretly about doors. Its oldest ancestor is the Proto-Indo-European root *dhwor-, meaning 'door' or 'doorway,' which split into two important Latin descendants: fores ('doors') and foris ('outside'). The logic was spatial: the door divided the known interior from the unknown exterior, and foris meant everything on the other side. Late Latin extended this to foranus ('on the outside'), which Old French inherited as forein or forain — describing people, goods, or customs from beyond one's own territory. Middle English borrowed it as forein in the thirteenth century. The modern spelling with -eign appeared later, probably influenced by the unrelated word 'reign,' creating one of English's more deceptive spellings. The same Latin root foris produced 'forest' (the wild land outside the settlement), 'forum' (the outdoor public space), and 'forensic' (originally pertaining to the forum, where legal cases were argued). Together, these words map a Roman's mental geography: the forum was the civilised outside, the forest was the wild outside, and the foreign was everything beyond both.