Meaning & use
constant
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Meanings
adjectivecomparable
Happening all the time or very frequently over a period.
Grammar: Usually before a noun (constant noise) or after linking verbs; compare 'more constant.'
Patterns
- constant interruptions
- a constant stream of something
The constant noise from the construction site made it hard to concentrate.
She lived in constant fear of losing her job.
adjectivecomparable
Staying at the same level or value and not varying.
Grammar: Often follows remain, keep, or stay: the temperature remained constant.
Patterns
- remain constant
- at a constant speed
- keep something constant
The temperature inside the greenhouse remains constant.
Light travels at a constant speed in a vacuum.
nouncountablemathematicsphysics
A quantity or value that stays the same in a particular calculation, equation, or situation.
Grammar: Countable noun; the plural constants appears in formulas and scientific laws.
Patterns
- a constant
- treat something as a constant
In the equation y = mx + b, b is a constant.
Planck's constant is a fundamental value in quantum physics.
Word forms
| comparative | more constant |
|---|---|
| superlative | most constant |
| plural | constants |
Common combinations
- constant companion
- Her dog was a constant companion during the long winter.
- constant speed
- The train moved at a constant speed for two hours.
- remain constant
- Interest rates are expected to remain constant this year.
- constant change
- Technology is in a state of constant change.
- constant pressure
- He works well under constant pressure.
Synonyms and how they differ
- continual
- Very close in meaning; continual often describes something repeated, possibly with breaks, while constant stresses no interruption.
- steady
- Regular and even, but steady can also describe controlled change at an even rate.
- permanent
- Means lasting indefinitely; constant describes something that does not vary or does not stop, not necessarily forever.
Opposites
Word family
- constantly adverb
- All the time or very often.
- constancy noun
- The quality of staying the same; also faithfulness.
- inconstant adjective
- Not steady or not faithful; rare and literary.
Commonly confused: constant or continual? constant or consistent?
constant vs continual
Continual usually describes something that happens repeatedly, often with breaks; constant suggests it never stops, though many speakers use them interchangeably.
constant vs consistent
Consistent means always matching or behaving the same way; constant means not changing in value or happening without stopping.
Practice
In the formula E = mc², c is a ___ that represents the speed of light.
Choose one answer.
A value that does not change in an equation is a constant; a variable is the opposite, and quotient and remainder are results of division.
Make it your own
Write a sentence using “constant”, then check it and compare it with the examples above.