Henry Hitchings, The Secret Life of Words
Anglo-Saxon words do the heavy lifting in our language. They represent the working class. Most of the words we use are among the oldest words in the language. These include words like go, come, know, good and work. They tend to be short and simple, but they don't impress anybody. When we want words with clout, we usually turn to those borrowed from other languages.
When the Normans conquered England in 1066, they brought the French language with them. Most of the English people went right on using the same words they had always used, but French became the language of royalty, the law, politics and economics. Some English kings didn't even speak English. To this day, nearly a thousand years later, we still us words like attorney, jury, evidence, prison, govern, peace and treaty with French origins. It is because of the Norman influence that we say we had pork or beef for dinner, not pig or cow. Doesn't that sound a lot better?
Another level of elitist words comes from Latin. These words stem not so much from the early Roman period in England as from the Renaissance period when Latin was considered the language of learning, as well as of the church. From Latin we got words like scientific, encyclopedia, literary, adjective. facsimile, minus and extraterrestrial.
To really make a good impression, especially if you have an advanced degree, you want to use words borrowed from Greek. That's where orthodontist comes from. So do such words as psychiatrist, pediatrician, paralysis, migraine, symmetry and almost every word that ends with -graphy or -ology (such as geography and geology).
English words from Latin and Greek have been called "SAT words" because they are more likely to show up in college-entrance exams. We may not know why, but most of us think we sound smarter when we use words other than those good old Anglo-Saxon originals.