IPA: /ˈfɔːrɪnər/
KK: /ˈfɔrɪnər/
A person who comes from a different country or place, often not belonging to the local community.
The conference was attended by many foreigners from around the world.
It is formed from "foreign" (from Old French *forain*, meaning outside) and "-er" (meaning a person who). A foreigner is a person from the outside.
Think of someone from 'outside' ('foreign') — and the '-er' just means a person. A foreigner is someone from outside.