mutable
gb/mjˈutəbəl/ us/mjˈutəbəl/
C1
English
Senses
0 senses
adjective
formal
C1
property
1
able to change easily
If something is mutable, it can change.
Usage pattern:
[something] is mutable
Common mistake:
Learners often use it where a simpler word like changeable or flexible is more natural in everyday speech.
Synonyms
changeable (More common and neutral in everyday English.)
|
variable (Often suggests differences over time, situations, or measurements.)
|
flexible (Emphasizes willingness or ability to adapt.)
Antonyms
unchanging (Stresses that it stays the same over time.)
|
fixed (Suggests it is set and not intended to change.)
|
constant (Emphasizes stability and regularity.)
Collocations
mutable nature
|mutable character
|mutable mood
|mutable emotions
|mutable plans
|mutable circumstances
|mutable environment
|mutable situation
Themes
describing_things
|change
Examples
- Public opinion is mutable and can shift quickly after a major event.
- In her twenties her ambitions were mutable, changing from month to month.
- The rules are not immutable; they are mutable and open to revision.
Learner examples
- My schedule is mutable, so I can meet you later.
- His mood is mutable.
adjective
technical
C1
property
2
changeable after being created (computing)
In programming, mutable means you can change it after you make it.
Usage pattern:
[data/object/structure] is mutable
Common mistake:
Do not confuse mutable (can be changed) with mutable vs. immutable as a specific programming design choice.
Synonyms
modifiable (General technical synonym; less tied to the mutable/immutable contrast.)
|
editable (Often used for user-facing content rather than program objects.)
Antonyms
immutable (Cannot be changed after creation.)
|
read-only (Not permitted to be changed, often by access rules.)
Collocations
mutable object
|mutable data
|mutable state
|mutable variable
|mutable structure
|mutable collection
|mutable reference
|mutable default argument
Themes
computing
|programming
Examples
- In this language, strings are immutable but lists are mutable.
- The bug happened because a mutable object was shared across threads.
- They switched to immutable data to avoid accidental changes to mutable state.
Learner examples
- A list is mutable, so you can add items to it.
Grammar
Dictionary form
mutable
IPA
GB/mjˈutəbəl/
US/mjˈutəbəl/
Syllables & stress
mut - able (2 syllables)
Stress on 1st syllable (mut)
Word forms
Adjective
- Base: mutable
Word family
Related words
mutant
noun B2
Negative and opposite forms
immutable
adjective
Advanced or less common
mutability
noun C1
immutability
noun
Expressions
mutable data
1/mjˈutəbəl dˈætə/
fixed phrase
technical
data that can be changed
Data you can edit or update.
Examples
- Use defensive copying when you accept mutable data from outside the module.
- Mutable data structures can be faster for frequent updates, but they require careful handling.
mutable object
1/mjˈutəbəl ˈɑbd͡ʒɛkt/
fixed phrase
technical
object that can be modified
A programming object you can change after creating it.
Examples
- Be careful when you pass a mutable object into a function, because the function may change it.
- A mutable object can cause surprising side effects when it is shared by different parts of a program.
mutable state
1/mjˈutəbəl stˈeɪt/
fixed phrase
technical
state that can change
Data in a program that can change.
Examples
- They reduced mutable state to make the code easier to test.
- Mutable state in a shared module can lead to hard-to-find bugs.