infinity

infinity — noun

1. The condition of continuing without any boundary or stopping point, especially w

1.nounB1
Definition

The condition of continuing without any boundary or stopping point, especially when thinking about the universe, time, or a quantity that never ends.

Example

Joon stared at the stars, trying to understand the idea of infinity.

the idea of infinity — abstract concept

The teacher explained that infinity has no beginning and no end.

Common collocations
  • the infinity of space
  • the infinity of time
  • idea of infinity
  • concept of infinity
Synonyms
  • endlessness

    more concrete and everyday; less abstract than infinity

  • boundlessness

    more formal or literary; emphasizes the lack of limits

  • limitlessness

    similar to boundlessness, slightly less formal

Antonyms
  • finity

    rare; the state of having limits

  • limitation

    different concept; refers to a specific restriction rather than the opposite of boundlessness

Grammar Patterns

the infinity of + noun (space, time, universe)

to / into infinity

Usage Note

Often used with 'of' to connect to a specific boundless thing, as in 'the infinity of space' or 'the infinity of time.' Common in philosophical, scientific, and poetic contexts.

Common Mistakes

The ocean stretched to eternity.
The ocean stretched to infinity.
'eternity' refers only to endless time, while 'infinity' covers both endless time and endless space.

2. A very distant location that appears unreachable, commonly describing something

2.nounB2
Definition

A very distant location that appears unreachable, commonly describing something moving away until it can no longer be seen.

Example

Gabriel watched the train move toward the mountains and disappear into infinity.

disappear into infinity — receding beyond sight

The dirt road stretched to infinity, with no houses or cars in sight.

Common collocations
  • into infinity
  • stretch to infinity
  • disappear into infinity
  • fade into infinity
Synonyms
  • the horizon

    more specific; the visible line where earth meets sky

  • the distance

    less dramatic; simply a faraway point

  • the beyond

    more poetic or literary; suggests something mysterious

Grammar Patterns

into infinity

to infinity

disappear / fade / recede into infinity

Usage Note

Almost always appears in the phrase 'into infinity' following verbs of movement or disappearance such as 'stretch,' 'fade,' 'disappear,' or 'recede.'

Common Mistakes

The mountain range went to the infinity.
The mountain range stretched into infinity.
'infinity' in this sense usually does not take the definite article 'the' and follows 'into' rather than 'to.'

3. In mathematics, a quantity that is greater than any number that can be named, us

3.nounB2
Definition

In mathematics, a quantity that is greater than any number that can be named, used in calculations about limits, series, and geometry, and shown by the symbol ∞.

Example

Faisal learned that in calculus the symbol ∞ stands for infinity.

symbol ∞ stands for infinity

The number line stretches in both directions without ever reaching infinity.

Common collocations
  • approach infinity
  • as x approaches infinity
  • infinity symbol
  • toward infinity
Synonyms
  • the infinite

    noun form used in formal mathematics and philosophy

  • limitlessness

    less technical; describes the quality rather than the mathematical concept

Antonyms
  • zero

    the opposite end of the number line in some contexts

Grammar Patterns

approach infinity

toward infinity

the symbol for infinity

Usage Note

In mathematics, infinity is not a number you can add, subtract, or multiply — it is a concept describing something without an upper bound. Frequently used in calculus when discussing limits.

Common Mistakes

Infinity is the biggest number.
Infinity is not a number
it is a concept for something without any limit.' — In math, you cannot use infinity in ordinary arithmetic like you would with actual numbers.

4. An amount or number that is so big it is hard to count or even picture.

4.nounB1
Definition

An amount or number that is so big it is hard to count or even picture.

Example

Quan had an infinity of apps on his phone and could not pick one.

an infinity of [apps/choices/things] — huge quantity

Adisa discovered there were an infinity of reasons to love his new city.

Common collocations
  • an infinity of choices
  • an infinity of reasons
  • an infinity of questions
  • an infinity of stars
Synonyms
  • countless

    adjective meaning too many to count; more common in everyday writing

  • myriad

    more formal or literary; suggests great variety as well as number

  • a huge number

    less emphatic; simply means very many

Antonyms

Grammar Patterns

an infinity of + plural noun

Usage Note

Used hyperbolically in everyday speech to mean 'a very large number' rather than literally endless. The phrase 'an infinity of' emphasizes that the number feels overwhelming or uncountable.

Common Mistakes

There are infinity choices.
There are an infinity of choices.
In this sense, 'infinity' must be preceded by the article 'an' and followed by 'of.'

Word family

  • infinite
    adjectiveB1
  • infinitely
    adverbB2
  • infinitude
    nounC2
  • infinitesimal
    adjectiveC2
  • finite
    adjectiveB2

Synonym discussion

Sense: noun/1

Infinity and eternity both describe something without end, but they cover different domains. Eternity refers only to time — something that lasts forever — while infinity covers both endless time and endless space. You can say 'the universe stretches to infinity' but not 'the universe stretches to eternity.' Boundlessness and limitlessness are closer synonyms for infinity, emphasizing the lack of boundaries or restrictions. Boundlessness is slightly more formal and often used in philosophical or literary writing ('the boundlessness of the ocean'), while limitlessness is more straightforward and can apply to both physical space and abstract potential ('the limitlessness of human imagination'). For everyday use, infinity is the most natural word for endless space or quantity, boundlessness fits formal descriptions of nature, and eternity should be reserved for time-specific contexts.

infinity ↗eternity ↗boundlessnesslimitlessness

Common collocations

Nouns

Phrases

  • an infinity of
  • to infinity and beyond
  • stretch to infinity
  • disappear into infinity
  • approach infinity

Prepositions

Etymology

LatinFrenchEnglish

Infinity comes from Latin 'infinitas,' meaning boundlessness or endlessness. The word was formed by adding the prefix 'in-' (not) to 'finis' (end, boundary). It entered English through Old French 'infinité' during the 14th century, initially with a religious and philosophical sense before expanding into mathematics.