flatten

American  

[flat-n] / ˈflæt n /

verb (used with object)

1. to make flat.

2. to knock down.

   The boxer flattened his opponent in the second round.

   Synonyms:

   floor, deck, prostrate, fell, ground

---

verb (used without object)

1. to become flat.

verb phrase

1. flatten out to fly into a horizontal position, as after a dive.

2. flatten in flat.

flatten British  

/ ˈflætən /

verb

1. (sometimes foll by out) to make or become flat or flatter

2. informal (tr)

   1. to knock down or injure; prostrate

   2. to crush or subdue

      failure will flatten his self-esteem

3. Usual US word: flat.  (tr) music to lower the pitch of (a note) by one chromatic semitone

4. to manoeuvre an aircraft into horizontal flight, esp after a dive

---

Other Word Forms

• flattener
  noun
• overflatten
  verb (used with object)
• unflattened
  adjective

Etymology

Origin of flatten

First recorded in 1620–30; flat ¹ + -en ¹

Explanation

When you flatten something, you crush it or level it out. If the recycling bin is getting full, you should probably flatten all those cans you're adding to it. You might flatten the batter in a cake pan before baking it, or flatten the grass along a path through a field. If your curly hair tends to get frizzy in humid weather, you may try to flatten it before you leave for school in the morning. You also might flatten yourself against a wall if you're hiding from your friend, or describe a terrible storm this way: "The tornado managed to flatten several buildings."

Example Sentences

We're here to find out what version of Fury we're going to see - the fleet-footed mover, or someone who has made a conscious decision to flatten his feet and rely more on upper-body movement.

From BBC • Apr. 9, 2026

Zuckerberg said on a recent earnings call that Meta is investing in AI-native tooling so individuals can get more done and the company can flatten some teams.

From The Wall Street Journal • Mar. 24, 2026

Moderate relief is in sight this weekend, when forecasters predict the powerful high pressure system will start to flatten out, bringing a gradual dip in temperatures.

From Los Angeles Times • Mar. 18, 2026

“We’re just seeing this trend flatten out,” Berner said.

From MarketWatch • Mar. 12, 2026

The girl with the frizzy curls licked her finger and slid it across a few strands on her forehead to flatten them down.

From "The Red Car to Hollywood" by Jennie Liu

Related Words

• crush
• raze
• smash
• straighten