1 B1 neutral
To give an animal more food so that it gains weight, especially before slaughter.
"The farmer spent the autumn fattening up the pigs before the winter market."
separable
fatten up
B1 informal separable transitive/intransitive
To make a person or animal heavier by feeding them more, or to become heavier by eating more.
In plain English
To make someone or an animal fatter by giving them lots of food.
What does "fatten up" mean?
3 meanings, ordered from most common to least. Color-coded by CEFR level.
2 B1 informal
To feed a thin person more in order to help them gain weight.
"Her grandmother immediately set about fattening her up with stews and fresh bread."
separable
3 B2 idiomatic informal
(Figurative) To increase the size, value, or attractiveness of something.
"They fattened up the offer with a signing bonus to attract better candidates."
separable
Literal vs figurative
Words literally mean
To make fat in a completed, thorough sense — 'up' implies completion.
Actually means
To make someone or an animal fatter by giving them lots of food.
Usage tip
Commonly used for livestock being prepared for slaughter, or humorously about people. Can sound negative when used about people. Often used in the pattern 'fatten up for...'
Words that pair with "fatten up"
Natural word combinations native speakers use most often.
cattle pigs children Christmas slaughter season
How to conjugate "fatten up"
The five tense forms you'll use most often.
Base
fatten up
I/you/we/they
3rd person
fattens up
he/she/it
Past simple
fattened up
yesterday
Past participle
fattened up
have + pp
-ing form
fattening up
continuous
Hear "fatten up" in the wild
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Other ways to say "fatten up"
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