After their military victory in 1066, the French added the language of a ruling elite to the English vocabulary--in government and law,
art and learning, fashion and social culture.
Because of the Norman Conquest English is rich in synonyms, or words that have similar meanings. To express an idea modern English speakers and writers can often choose among a French word, which is likely to be more sophisticated; a Latin word, which is probably more scholarly; and an Old English word, which will be the oldest and plainest of all.
These words are a small part of the French contribution to English.