The word Talmud and Gemara is used to refer to the written down Oral Law (written down somewhere between 500CE-1000CE?). What is the English translation of those two words and why were they chosen/used to refer to the Oral Law?
גמרא means תלמוד in Aramaic, that's simple - לגמור in Aramaic equals to ללמוד in Hebrew. And Talmud means "learning" - the action/process of "to learn".
The Talmud is just a compendium, it is a book, not the complete teaching - a "handbook of the Oral Law":
- There are lots of topics completely missing from it and covered by other books. Partially because some topics (and whole Mitzvos) are missing from the underlying Mishna.
- There are topics not related to the Oral Law - culture, science, language, history, economics and more