- The striking of one body against another; collision. See Synonyms at collision. (noun)
- The force or impetus transmitted by a collision. (noun)
- The effect or impression of one thing on another: still gauging the impact of automation on the lives of factory workers. (noun)
- The power of making a strong, immediate impression: a speech that lacked impact. (noun)
- To pack firmly together. (verb-transitive)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.