Incorrect spelling


Incorrect spelling, explanation: this form is a misspelling (maybe due to prefixes used before some adjectives in- and im-; impact is however not a word with prefix, but a separate word). Impact comes from Latin word impactus (past participle form of impingere).

Correct spelling


Correct spelling, explanation: this is a word originating in Latin impactus; only this shows us that this is the correct pronunciation. Also, inpact (an incorrect form) is probably mistaken with prefix in-; impact however is a separate, independent word.

Definition of impact:
noun, strong influence on, a forceful contact
In physics direct, forceful and sudden collision of two bodies is called an impact.
My college years had an impact on me. I learned how to work hard.
verb, to make contact, usually forcefully