flat·ten | \ ˈfla-tᵊn \
flattened; flattening\ˈflat-niŋ, ˈfla-tə- \

Definition of flatten 

transitive verb

: to make flat: such as

a : to make level or smooth

b : to knock down also : to defeat decisively

c : to make dull or uninspired often used with out

d : to make lusterless flatten paint

e : to stabilize especially at a lower level

intransitive verb

: to become flat or flatter: such as

a : to become dull or spiritless

b : to extend in or into a flat position or form

c : to become uniform or stabilized often at a new lower level usually used with out

Keep scrolling for more

Other words from flatten

flattener \ˈflat-nər, ˈfla-tə- \ noun

Synonyms & Antonyms for flatten


even, level, plane, smooth


rough, roughen

Visit the Thesaurus for More 

Examples of flatten in a Sentence

Dozens of houses were flattened by the tornado. The boxer was flattened in the seventh round. The team got flattened in the first round of the play-offs. Prices are expected to flatten after the holiday shopping season.
See More

Recent Examples on the Web

Khalid Boutaib was flattened by Jose Fonte in an aerial challenge that again had the Moroccans up in arms, with Renard warned for gesturing for the video assistant referee. Martyn Wood, chicagotribune.com, "Ronaldo again leads Portugal to victory against Morocco," 20 June 2018 Check on pie shell after 5 minutes; if the bottom has puffed up, gently press down by hand to vent steam and flatten it. Ann Maloney, NOLA.com, "Former waitresses' 'lazy' strawberry pie wins 'Waitress the musical' contest," 1 June 2018 Eighteen science facilities were flattened during the Gulf air campaign, according to deputy minister Musawi, including the Tuwaitha nuclear reactor, which nearly melted down when it was struck without its protective shield. Peter Schwartzstein, Smithsonian, "How Saddam and ISIS Killed Iraqi Science," 30 May 2018 If cooking boneless skinless chicken breasts, put them first in a zipper-lock plastic bag and flatten them to an even thickness by whacking with a rolling pin. Nancy Stohs, Milwaukee Journal Sentinel, "5 meats to master on the grill: We went back to school to learn the best techniques," 29 May 2018 Low-level electrical activity in neurons increases in colder temperatures whereas warmer temperatures flatten it. Dana G. Smith, Scientific American, "Sound Awake: “Noisy” Neurons May Repeatedly Disrupt Your Sleep," 1 May 2018 Gather dough together, pushing and working it into a ball, then flattening it, until only a few dry spots remain. Chris Morocco, Bon Appetit, "Fruit Galette with Buckwheat Crust," 26 Mar. 2018 Separate dough into 8 biscuits and flatten them into 3 1⁄4-in. rounds. Woman's Day Kitchen, Woman's Day, "Jelly Doughnut Holes," 29 Nov. 2010 After the dough has rested, use the palm of your hand to flatten the dough into circles about 1/4-inch thick. Daniel Neman, sacbee, "Artistry, flavor blends are marks of Moroccan," 10 July 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'flatten.' 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 flatten

1630, in the meaning defined at transitive sense

Keep scrolling for more

Learn More about flatten

Statistics for flatten

Last Updated

19 Sep 2018

Look-up Popularity

Time Traveler for flatten

The first known use of flatten was in 1630

See more words from the same year

Keep scrolling for more

More Definitions for flatten



English Language Learners Definition of flatten

: to make (something) flat or flatter

: to become flat or flatter

: to knock down (something or someone)


flat·ten | \ ˈfla-tən \
flattened; flattening

Kids Definition of flatten

: to make or become flat She flattened herself against the wall.

Keep scrolling for more

Comments on flatten

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


by word of mouth

Get Word of the Day daily email!

Test Your Vocabulary

Name that Food Quiz

Name That Thing

Test your visual vocabulary with our 10-question challenge!


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!