Note also "What I Am Is What I Am" by Edie Brickell, and "You Are What You Is" by Frank Zappa.

The Tao Te Ching seems to be of two minds on the matter. On the one hand, there's the repeated lesson that what you call something doesn't determine its nature, but on the other you have:

That which is, is. That which is not, is. There is not that which is not.

Which in less spiritual terms means that as long as you can conceive of something, whether it has any physical existence or not, exists as a notion in your mind.

Apropos of Magritte, I've been using the following image as my signature on eBay's discussion forums for some time now:
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The text at the right of the picture says "this is not a pipa", a pipa being the mandolin-like instrument shown at the left, and pronounced very approximately like the French "pipe".

Not to disagree with you, but just to be more specific, I gather that the "-itis" ending means not merely something wrong but specifically inflammation, so it carries at least a little more information.  My own favorite is "syndrome"; we have terms like "Sudden Infant Death Syndrome", "Auto-Immune Deficiency Syndrome" and, I forget, that thingy that sometimes happens to soldiers after long stretches in combat—post-traumatic stress disorder, maybe?—and we call them syndromes and their victims are sometimes comforted by the official-sounding term.  But it doesn't mean we understand anything about it; it just means that someone has described a set of symptoms and/or behaviors.  It's named a "syndrome" because we don't, at the time, know what causes it.  Sometimes it keeps the name after they figure out more about it (as with AIDS), but in other cases we don't even know whether the cause is physical, psychological or spiritual.

My best friend in high school moved away only shortly after we met, so we kept up via letters and, decades later, email.  We still write, and I still think of him as my best friend even though we've been in each other's presence only a handful of times in 40 years.  Anyway, a decade or so ago we started compiling a list of common sayings that appear to be tautologies but aren't—that is, that have the form of tautologies but really say something more.  Here are some of them:

A deal's a deal.
A man's gotta do what a man's gotta do.
Boys will be boys.
Business is business.
Fair is fair.
First things first.
He wants what he wants when he wants it.  (said of children)
I gotta be me.
If we had ham, we could have ham and eggs, if we had eggs.
Que será, será.
Rules is rules.
That's that.
The law's the law.
The way to learn a language is to sit down and learn it.
Tomorrow is another day.
When you're right, you're right.
When you gotta go, you gotta go.

Yogi Berra is remembered for this kind of thing.  "You can observe a lot just by watching" and "It ain't over 'til it's over" are two famous ones.  Then there are some enshrined in our media:
"A horse is a horse, of course, of course…"
"Forever's a long time, sweetheart."
"We're all here to do what we're all here to do."
"When it comes to the future, the only way to get there is to get there."
Q: Worf, how can I convince you I'm mortal?  Worf: Die.