TYPICAL ERROR Your suggestion is quite unpractical.
CORRECTION Your suggestion is quite impractical.
EXPLANATION To make the negative versions of words, we often attach prefixes: for example, believable becomes unbelievable but credible becomes incredible. (The logic is that in- tends to be used if the word comes from Latin. Note also that the ending is -ible for Latin words but -able for 'English' words: incredible, unbelievable.) While un- and in- are most frequently used as negative prefixes, there are others. Here are guidelines for which prefix to choose with which words:
- The prefix im- is used before many words beginning with m or p (for example impractical, improper).
- The prefix il- is used before many words beginning with l (for example illegal, illogical).
- The prefix ir- is used before many words beginning with r (for example irrelevant, irreversible).
Add a prefix to each of these words to create its negative form. For example, believable would become unbelievable and credible would become incredible.