1 A2 neutral
To make a physical surface level and free of bumps or curves.
"Use a rolling pin to flatten out the dough into a thin sheet."
separable
flatten out
B1 neutral separable transitive/intransitive
To become or make something flat, level, or to stop increasing or decreasing.
In plain English
To make something go from bumpy or curved to totally flat, or when growth stops and things stay the same.
What does "flatten out" mean?
3 meanings, ordered from most common to least. Color-coded by CEFR level.
2 B2 idiomatic neutral
To stop increasing or decreasing and remain at a steady level (of rates, trends, or curves).
"Inflation has begun to flatten out after months of sharp rises."
inseparable
3 B2 idiomatic informal
To lose energy or momentum; to become dull or less effective.
"The team's performance flattened out in the second half of the season."
inseparable
Literal vs figurative
Words literally mean
To extend flat outward — transparent for the physical sense, slightly idiomatic for the trend/economic sense.
Actually means
To make something go from bumpy or curved to totally flat, or when growth stops and things stay the same.
Usage tip
Very common in finance, economics, and science to describe a curve or trend reaching a plateau. Also used literally in cooking and construction.
Words that pair with "flatten out"
Natural word combinations native speakers use most often.
curve growth inflation dough road terrain
How to conjugate "flatten out"
The five tense forms you'll use most often.
Base
flatten out
I/you/we/they
3rd person
flattens out
he/she/it
Past simple
flattened out
yesterday
Past participle
flattened out
have + pp
-ing form
flattening out
continuous
Hear "flatten out" in the wild
Listen to native speakers using "flatten out" in real YouTube videos — click a clip to watch it on Looplines.
Keep exploring
Jump to every phrasal verb built on the same verb, particle, or level.