Use of obscure words like “ebulliate”

In a belletristic context, go for it; why not? Trust your instincts.

Some rules of thumb. It's in bad taste to use an obscure word just because you can; use obscure words only when you think their obscurity undeserved. Remember that elegance and sonorousness are qualities of a composition as a whole, not its vocabulary; you cannot season good writing into bad by sprinkling it with piquant polysyllables. As a writer what you find obvious from context will less so to your readers; avoid obscure words in the sentences and phrases your intention hinges on. In short: if you could say it out loud without sounding like you've been reading "How To Increase Your Word Power," you're probably safe.

In other contexts, it's inadvisable; certainly you shouldn't drop "ebulliate" on the readers of a technical reference.

Yes, Paul, I agree - it's never clever to use words just to sound smart. In the instance I was referring to, I couldn't find a word to fit my intended meaning better, so I went with "ebulliate," even though it's obscure. But you make a very good point! Nobody likes a pretentious writer!

I'd say, know your audience and the situation. I assume when you communicate with someone, it's your intention to have them understand you. If that's at risk, consider choosing your words more carefully. If it's in writing and a particular word conveys some subtlety of meaning that suits your purposes particularly well, then your reader may have the opportunity to look it up if needed. On the other hand, if you are talking to someone, say, at work, maybe to your boss or something, don't say something you know will be unintelligible. It probably won't score you any points.

On the subject of sesquipedality—the use of big words—Bryan Garner has this to say:

"Build your vocabulary to make yourself a better reader; choose simple words whenever possible to make yourself a better writer." (A Dictionary of Modern American Usage)

That is sound advice. Of course, obscure* is not the same as simple, but the principle applies to both kinds. If you find yourself wondering whether a word is "too smart for the room," then it probably is. Paul and Porsche have made essentially the same point. Still, I might be tempted to drop "ebulliate" on readers of a technical reference, Paul, just to wake them up.

*See John McIntyre's comments on "limn" here:

http://weblogs.baltimoresun.com/news/mcintyre/blog/2010/09/wind_and_limn.html

Use whatever word you need to use to best say what you want to say.

Obviously words no one recognizes are rarely going to be best, but there will be times . . ..