im·​pac·​tor | \ im-ˈpak-tər How to pronounce impactor (audio) \
variants: or impacter

Definition of impactor

1 : a machine (such as a steam or air hammer or a pile driver) or part that operates by striking blows

Examples of impactor in a Sentence

Recent Examples on the Web After smashing into Pallus some 1.7 billion years ago, the impactor might have shattered into fragments, which then drifted out into space and began to trail their leader. Katherine J. Wu, Smithsonian Magazine, "The Most Cratered Object in the Asteroid Belt Looks Like a Golf Ball," 13 Feb. 2020 Scientists have suggested that the impactor was about 10 percent of the mass of Earth — just larger than Mars. Fox News, "5 interesting facts about the moon," 16 Mar. 2020 Further Reading End-Cretaceous asteroid impact seems to have juiced seafloor volcanoes After the skies cleared, potent global warming set in for the long haul due to the CO2 produced when the impactor evaporated bedrock to make the impact crater. Scott K. Johnson, Ars Technica, "End-Cretaceous mass extinction saw big swings in ocean pH," 24 Oct. 2019 After the large impactor smashed into the planet, some of the debris formed a disk that flew up to circle the Martian equator. Nola Taylor Redd,, "Giant Impact May Have Created Mars' Moons," 18 Apr. 2018 This consisted of a lunar orbiter and an impactor that helped confirm the existence of water ice on the Moon. Eric Berger, Ars Technica, "India has launched an ambitious mission to the Moon," 22 July 2019 Computer simulations also revealed that the impactors responsible for Pallus’ craters were traveling at speeds over 25,000 miles per hour—nearly twice as fast as is typical for asteroid belt collisions, reports Charles Q. Choi for Katherine J. Wu, Smithsonian Magazine, "The Most Cratered Object in the Asteroid Belt Looks Like a Golf Ball," 13 Feb. 2020 To figure out how the asteroid family could have formed, the researchers built a model that allowed them to try out different collisions, testing different impactor sizes and angles of impact. John Timmer, Ars Technica, "Collision liquified the 4th-largest asteroid, turning it into a dwarf planet," 29 Oct. 2019 This mission will use a kinetic impactor to try and deflect the smaller component of the binary asteroid, Didymos, which has a diameter of 160 meters. Eric Berger, Ars Technica, "It looks like NASA is getting serious about finding hazardous asteroids," 23 Sep. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'impactor.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of impactor

1872, in the meaning defined at sense 1

Keep scrolling for more

Learn More about impactor

Time Traveler for impactor

Time Traveler

The first known use of impactor was in 1872

See more words from the same year

Statistics for impactor

Last Updated

23 Aug 2020

Cite this Entry

“Impactor.” Dictionary, Merriam-Webster, Accessed 27 Sep. 2020.

Comments on impactor

What made you want to look up impactor? Please tell us where you read or heard it (including the quote, if possible).


Test Your Vocabulary

Challenging Vocabulary Quiz Returns!

  • stylized drawing of woman pole vaulting across gap to get trophy
  • Which is a synonym of fuliginous?
Spell It

Can you spell these 10 commonly misspelled words?

Bee Cubed

Test Your Knowledge - and learn some interesting things along the way.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!