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im·pact (ĭmpăkt)
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n.
1.
a. The striking of one body against another; collision. See Synonyms at collision.
b. The force transmitted by a collision.
2. The effect or impression of one person or thing on another: still gauging the impact of automation on the lives of factory workers.
v. (ĭm-păkt, ĭmpăkt) im·pact·ed, im·pact·ing, im·pacts
v.tr.
1. To pack firmly together.
2. To strike forcefully: meteorites impacting the lunar surface.
3. To have an effect or impact on: "No region ... has been more impacted by emerging ... economic trends" (Joel Kotkin).
v.intr.
To have an effect or impact. See Usage Note below.

[From Latin impāctus, past participle of impingere, to push against; see IMPINGE.]

im·paction n.

Usage Note: Impact in the figurative sense of "a dramatic effect" came under criticism in the 1960s, both as a noun and verb. Complaints that the noun was a pointless hyperbole and a vogue word turned out to be short-lived, and this usage is now is standard: in our 2015 survey, 97 percent of the Usage Panel accepted The program might have a positive impact on our nation's youth. (A similar sentence was accepted by 93 percent of the Panel in 2001.) The verb is a different matter. Many people dislike it because they assume it was converted from the noun in the manner of voguish and bureaucratic words like dialogue and interface, but in fact impact was a verb long before it was a nounthe verb dates from the early 1600s, the noun from the late 1700s. Most of the Panelists still disapprove of the intransitive use of the verb meaning "to have an effect": in our 2015 survey, 78 percent of the Panel (down only slightly from 85 percent in 2001) rejected These policies are impacting on our ability to achieve success. The transitive version was once as vilified, but is gradually becoming more acceptable: in 2015, only 50 percent (down from 80 percent in 2001) rejected The court ruling will impact the education of minority students, and only 39 percent (down from 66 percent in 2001) found the literal sense unacceptable in the sentence Thousands of meteors have impacted the lunar surface. Although resistance to the transitive senses is waning, the intransitive use is still strongly disliked and is best avoided. See Usage Notes at contact, impactful.

The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2016 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
 

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