From Latin porticus 'colonnade,' from porta 'gate' — the same root that gives us portal and port.
A covered shelter at the entrance of a building.
From Old French porche 'porch, vestibule,' from Latin porticus 'colonnade, arcade,' from porta 'gate.' The architectural sense has been stable since Roman times — a covered entrance attached to a building. Key roots: *per- (Proto-Indo-European: "to lead