# infinity

/ˌɪnˈfɪnɪti/ (US) · /ɪnfˈɪnɪti/ (UK)

Source: https://englishreference.com/word/infinity
Updated: 2026-06-20

## Senses

### 1. endlessness

noun · CEFR B2

the state of having no end or limit in time, space, or amount.

For teachers: the quality of being infinite; an unlimited extent of time, space, or quantity.

- The stars seemed to stretch out into infinity in the dark night sky.
- Philosophers have long debated whether the universe is truly a state of infinity or if it possesses a boundary that remains beyond human observation.

### 2. mathematical value

noun · CEFR B2 · Technical

a number or value that is larger than any other number you can think of.

For teachers: a mathematical concept representing a quantity larger than any finite number, often treated as a limit.

- In math class, we learned that some sequences of numbers go toward infinity.
- The function approaches infinity as the value of x nears zero from the positive side.

Usage: Often used with the preposition 'to' in the phrase 'to infinity'.

### 3. the symbol

noun · CEFR C1 · Technical

the mathematical symbol (∞) that looks like a sideways number eight.

For teachers: the typographic or mathematical character ∞ used to represent an infinite quantity.

- The professor wrote the symbol for infinity on the chalkboard.
- The lemniscate, commonly known as the infinity symbol, was first introduced in a mathematical context during the seventeenth century.

### 4. optics/distance

noun · CEFR C2 · Technical

a distance that is so far away that light rays from it arrive in straight, parallel lines.

For teachers: a distance that is effectively infinite relative to the focal length of an optical system.

- When the camera lens is set to infinity, distant mountains will be in focus.
- For the purposes of this experiment, any light source placed more than ten metres away can be considered to be at infinity.

Usage: Usually appears in the phrase 'at infinity'.

## Examples

- The stars seemed to stretch into infinity.
- The professor explained that some sets of numbers are larger than others, even though both reach toward infinity.
- Philosophers and mathematicians have long debated whether infinity is a physical reality of our universe or merely a conceptual tool used to solve complex equations.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.