1. a person who writes a novel, poem, essay, etc.; the composer of a literary work, as distinguished from a compiler, translator, editor, or copyist.
2. the literary production or productions of a writer: to find a passage in an author.
3. the maker of anything; creator; originator: the author of a new tax plan.
4. Computers. the writer of a software program, especially a hypertext or multimedia application.
verb (used with object)
5. to write; be the author of: He authored a history of the Civil War.
6. to originate; create a design for: She authored a new system for teaching chemistry.
As you can see the the term doesn't only apply to writers, but crosses all areas of production and creation not just writing. It stems from an old French word meaning "to give authority to" do something. Innately, you have the right to publish, sell, dispose, or anything else with your creation.
Your may notice that I use the term "writer" instead of "author" when speaking of the process of creatiing books. This is why. While both terms are interchangeable among writer circles, it is not when viewed worldwide.
Why? Because, you are geared towards publishing your work when it is finished unlike a journal or diary that you write for personal consumption. Unlike may who keep their journals private, blogging makes it visible for all to see, therefore it's authoring.
Another contention is you become an author when you publish your book or novel. While both are correct in the literal sense, I don't agree as much with this one. To me, it means you are spinning your wheels doing nothing while writing and editing. Writing and editing is important. Without the above to you would have nothing to sell or publish.
While I may use the term "writing" or writer" in this blog, it's the distinction between the process and the end product. I will always be a writer with the hope to publish. Honestly, not all my writing is publishable even in today's world as an indie author. Sometimes the story just doesn't work.
Keep writing and loving the Lord.