noun /ˈpɪdʒɪn,ˈpɪdʒən/
an amalgamation of two disparate languages, used by two populations having no common language as a lingua franca to communicate with each other, lacking formalized grammar and having a small, utilitarian vocabulary and no native speakers.
Middle English likely began as a pidgin between the Norman invaders and the Anglo-Saxon-speaking (Old English) occupants of Britain. Otherwise, how could they have gotten any business done?
See Also: pidgin English, Pijin
Wikipedia foundation.