decrease

decrease — verb

1. what happens when the level of something — such as a price, temperature, or popu

1.verbtransitive / intransitiveB1
Definition

what happens when the level of something — such as a price, temperature, or population — drops to a lower point. It can also be used when a person takes action to bring a level down on purpose.

Example

Xiu's doctor decreased the dosage of her medication after her blood test results improved.

transitive: decrease + noun phrase (dosage)

The number of visitors to the national park decreased sharply after the wildfire last summer.

intransitive: decrease + adverb (sharply)

Common collocations
  • decrease significantly
  • decrease gradually
  • decrease steadily
  • decrease dramatically
  • decrease sharply
Synonyms
  • reduce

    Almost always transitive — you reduce something. Decrease can be both transitive and intransitive.

  • drop

    Suggests a more sudden or steep change; often used for prices, temperatures, or numbers.

  • decline

    Emphasizes a gradual, continuous reduction, especially in quality, health, or numbers.

  • lessen

    Focuses on reduction in degree or intensity rather than quantity; less common in formal data contexts.

Antonyms
  • increase

    The direct opposite — to become larger or make something larger.

Grammar Patterns

decrease + by + amount/percentage

decrease + adverb (significantly / sharply / gradually)

decrease + noun phrase (transitive)

decrease from X to Y

Usage Note

Frequently used with by + number or percentage to state how much something changes. Both transitive (someone decreases something) and intransitive (something decreases) uses are common.

Common Mistakes

The price decreased down by 10%.
The price decreased by 10%.
Decrease already includes the idea of moving downward; do not add 'down.'
I decreased the volume more small.
I decreased the volume.
Decrease already means 'make smaller'; do not add 'more small' or 'less.'

decrease — noun

Word family

  • decreasing
    adjectiveB2
  • decreased
    adjectiveB2

Synonym discussion

Sense: verb/1

All five words describe something moving downward in number, size, or degree, but they differ in how and where they are used. Reduce is almost always transitive — you reduce something deliberately, like costs or speed. Decrease works both transitively and intransitively, making it more flexible. Drop and fall are intransitive and suggest a faster or more noticeable change: prices drop, temperatures fall. Decline emphasizes a gradual, continuous reduction and often carries a slightly negative tone, especially in health or quality contexts ('his health declined'). Lessen is the mildest of the group and focuses on reduction in intensity or severity rather than quantity — you lessen pain, fear, or tension, but you rarely lessen a number. In writing, 'the number of visitors decreased' sounds neutral and factual, while 'the number of visitors fell' sounds more dramatic, and 'the number of visitors declined' implies an ongoing trend.

drop ↗fall ↗reduce ↗decline ↗lessen

Common collocations

Nouns

Adverbs

Phrases

  • on the decrease
  • a decrease in something
  • a decrease of something

Prepositions

Etymology

LatinOld FrenchEnglish

Decrease entered English in the 14th century through Old French 'decreistre,' which came from Latin 'decrescere' — a combination of the prefix 'de-' (meaning 'down' or 'away') and 'crescere' (meaning 'to grow'). So the word literally carries the sense of 'growing down' or 'un-growing' — a downward change in size or amount.