Moby-Dick by Herman Melville contains more than 17,000 unique words. Reading that novel (which I highly recommend) means that you will almost certainly have a larger vocabulary when you’re done, although much of that new vocabulary might be 19th century whaling jargon, which may not make you a sought-after conversational partner. Or maybe it would. What do I know?
There’s a certain school of thought among writers that you should endeavor to include as many “dollar words” (sometimes called SAT words after the test where you often encounter unusual or arcane verbiage) as you can, or that you should seek out a lot of unusual synonyms so you can have a lot of variety in your writing. There’s an opposite school of thought that thinks you should always write in a clear, simple manner that conveys what you want to convey without making the reader resort to a thesaurus.
The real answer is more complex: Use dollar words if you can pull it off.
The Problem of Tags
A note, though, on dialog tags. Sometimes when you’re writing a story you notice that Writing “he said” “she said” over and over again seems repetitive, and you’ll be tempted to substitute other words. He exclaimed! She hissed! But there’s a definite diminishing return to this; while popping in a “hissed” or “shouted” once in a while makes sense, doing it too much makes your writing a bit purple and overheated. Simply put, most of your dialog tags should probably be “said.”
However! There are no rules. If Cormac McCarthy can write entire novels without punctuation because he hates us, you can of course write a novel where everyone hisses, exclaims, and declares things.
That’s the rub when it comes to writing. A genius can break every rule and we still read the book, because genius. So can you use every bizarre word you can find in your prose and still write (and sell) a successful novel? Of course. You just have to pull it off. And pulling it off involves having a plan—a reason why these oddball words are the better choice. Simply doing it to show off all those years you spent reading the dictionary for fun ain’t gonna cut it.
But if, upon finishing your book and showing it around, you’re not getting the response you want, one of the first things you can do is strip out the dollar words and go for a simpler approach. That, or add in some vampires. People love vampires.
Whaling jargon sounds handy when the holiday party small talk fizzles (and the dollar words have failed to impress).
Hey Uncle Jim, let’s have a gam about how Mom’s biscuits are like hardtack, and then we can go pick some oakum out of the junk in the backyard.