“Impact” is not only a noun, but also a verb.

The 2003 edition of Garner’s Modern American Usage says, “Impact has traditionally been only a noun. In recent years, however, it has undergone a semantic shift that has allowed it to act as a verb.” But according to the Oxford English Dictionary, the shift isn’t so recent. The OED includes a definition of impact as a verb, and give examples of this usage dating back to the 17th century.

But if you use impact as a verb, please use it well—otherwise the word will lose some of its, well, impact. My Oxford American Dictionary carries this advice, which I endorse:

As a verb, impact remains rather vague and rarely carries the noun’s original sense of forceful collision. Careful writers are advised to use more exact verbs that will leave their reader in no doubt about the intended meaning. In addition, since the use of impact is associated with business and commercial writing, it has a peripheral status of ‘jargon,’ which makes it doubly disliked.

Comments

[Mark Adler]

Under what circumstances could "impact (up)on" be preferable to "affect"?

[Ray]

My own opinion: Use impact when you mean, literally, impact — one object colliding with another. While it’s not necessarily an error to use impact figuratively to mean affect or influence, other words (like affect or influence) serve the purpose better.

[Benjamin Opipari]

To me, "impact" is stronger than "affect." So something that impacts something else has a greater influence on that thing. "Affect" seems more indirect. But that's just me.

I think I see "impact" as stronger exactly because of your opinion, Ray, that it has to do with colliding.

[RNM]

You omitted the following, with which I agree:

The use of "impact" as a verb "would be perfectly acceptable if impact were performing any function not ably performed by 'affect' or 'influence.' If 'affect' as a verb is not sufficiently straightforward in context, then the careful writer might use 'have an impact on,' which, though longer, is probably better than the jarring impact of 'impacted.' Reserve impact for noun uses and 'impacted' for wisdom teeth.

Interestingly, 'impact' as a verb might have arisen partly in response to widespread diffidence about the spelling of 'affect.'"

Bryan A. Garner, Garner's Modern American Usage 445 (2009)