How do you tell one thesaurus from another? They're all so doggone / darn / gosh-darn / danged similar.
Here's one way, which I invented this morning while teaching.
During a conversation about reading strategies, one of my students suggested the thesaurus as a place to look up unfamiliar words. "That's a good emergency option if you don't have a dictionary," I said. "But thesauruses just can't list as many entry words as a dictionary can. For instance, my guess is that you'll find 'pulchitrudinous' as a synonym for 'beautiful,' but not the other way around."
She seemed a little dubious, so I said to grab a random thesaurus off my pile of random thesauruses, and test my theory.
Of course, the first one she opened had "pulchitrudinous" as its own entry.
I laughed and admitted that I hadn't chosen the best example, but that my reasoning was generally still sound. After class ended, I checked the rest of the thesauruses--big ones, small ones, medium-sized ones, college editions or average Joe versions, even Roget's II. Turns out about half of them had "pulchitrudinous" or "pulchitrude" as its own entry. (I was doubly disappointed that The Superior Person's Book of Words didn't include the term. Perhaps it's not as uncommon as I had hoped.)
So that's when I turned lemonade into an Arnold Palmer, and devised this handy way of picking a good thesaurus. Open it up to P, and if it has "pulchitrudinous" or "pulchitrude" as an entry (usually "Pulchitrudinous: See beautiful"), you're probably / likely / possibly / potentially holding a good one.
Of course, Firefox's automatic spell-checker, which dutifully underlines every perceived orthographical slight, doesn't recognize "pulchitrudinous" or "pulchitrude" as legitimate.