is there any rule for choosing negative prefix?

[Irene29]

I'm often mistaken when I need to form a word with the help of negative prefix. Is there any rule for choosing negative prefix?
For example, why should we use prefix -in but not -un in the word inappropriate ('he was using very offensive language that I thought was quite inappropriate to the situation')? Or is it necessary to look up the words with negative prefixes at a dictionary and learn them by heart?
Thanks in advance!

[Mordant]

Looking them up is easily the best option. There is no such word as "unappropriate." There is no rule that will help you figure this out. When it comes to solid words listed in a dictionary, you are not "choosing" negative prefixes -- they are fixed and not subject to choice. Memorization is essential.

[Our Tort System]

I'm a student of English and I concur with Mordant.
There are guidelines that help you choose the correct prefix but there are hosts of exceptions to such guidelines. I gave up on the guidelines long ago, I've come to rely on my memory in such matters.
You're way better off with learning adjectives by heart.
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[Alan]

Hi Irene,

There are so many anomalies as to why a particular negative prefix should be used in place of another that it would be a difficult task to make a general rule. It depends very much on the history of the word, the sound of the word and similarity with other words. You could check in a synonyms and antonyms dictionary but my advice is to try to remember the negative form when you first hear/see it in context.

Alan
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English as a Second Language
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