Instable VS unstable

"instable" is not a word; the prefix "in-" is not correct for this word. The correct form for "not stable" is "unstable".

Then howcome both dictionary.com and oxford list it as meaning 'not stable'?

Do you mean you saw "instable" in those dictionaries?? Or did you see the noun form, instability?

The adjective form of not stable is indeed unstable. But the noun form, not having stability, is instability.

I saw the adjective form as instable:

http://dictionary.reference.com/browse/instable

Hmmm. The World Engish Dictionary says it's 'less common' ... **** yes it's less common. In all my years (50+) I have NEVER seen or heard the word 'instable'. My advice is to forget that, at least in regard to American English. Just use unstable or instability.

Thanks

Newsflash, the rest of the world doesn't speak American english. Instable comes from the queens english which you americans need to adopt back into your hacked vocabulary

English is an ever evolving language, and the differences in our language have helped it become the worlds most powerful language

AnonymousNewsflash, the rest of the world doesn't speak American english. Instable comes from the queens english which you americans need to adopt back into your hacked vocabulary

As for the adjective, both instable and unstable are used without any difference in meaning.
As for the noun, just instability is used and unstability is not an English word.
Cheers
Hamid