Isn’t it odd?

goossun:

You made the word according to known English rules, but no such word actually exists. instead you'd use "oddness" or even just "oddity" as an adjective, or use a synonym that fits in context, such as "unique" or "peculiar."

"Oddness" is the quality of being odd. For example: "The oddness of his appearance makes him easy to spot." It's not very common in speech; "strangeness" means the same thing and is more common.

An "oddity" is a particular *thing* that is odd. You wouldn't use it when talking about people, though. (You might say "He's an odd one" instead, but that's a bit formal.) Again, it's not very common in speech.

They're not adjectives, they're nouns (which I'm sure is what speedwell meant).

(Boring stuff: Normally "-ity" (which comes from Latin) gets attached to words that come from Latin, French, and so on. "-ness" (which comes from Old English) gets added to words that came from Old English. "Odd" is strange because it works with both -ity and -ness.)

So I just wonder why can't one create the new word, "odditiness". I mean what's the red line of right or wrong when it comes to composing new words? I have before mentioned that Derrida for instance distinguishes between "irrepresentablity" and "unrepresentablity".
http://painintheenglish.com/post.asp?id=133

I know that I still have problems to speak simple English, but there are times when one needs to compose new words. So there must be a measure.

Oh, God, Derrida. That man is completely incomprehensible in French, let alone in English translation. Besides that, he is utterly unreliable when it comes to mathematical terminology, which he misunderstands in any language.

"There must be a measure."

There is; the measure is whether your new word actually communicates what it is meant to communicate.

The creative name of your photo, "Irreddenable Blue," is immediately clear. A word like "oddityness" is... well one thing that strikes me as wrong about it is that the hearer first hears a word that he knows ("oddity") and then, unexpectedly, the orphaned suffix. It's a stumbling block where "irreddenable" is not.