A pidgin is a simplified language that is usually formed from elements of two different languages — allowing basic communication between groups of people who don't share a common tongue.
If you're visiting Mexico but you don't speak Spanish, you may use a kind of pidgin to talk to locals — a combination of Spanish and English. Or the locals may speak a pidgin version of English to communicate with you. Most pidgins include various elements of different languages in addition to the primary source of vocabulary — but they're all made up. The word pidgin is thought to derive from a Chinese pronunciation of the word business as "bigeon" and eventually "pidgin."