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infinity

n.
US //ˌɪnˈfɪnɪti// UK //ɪnfˈɪnɪti// in·fin·i·ty
  1. 1 endlessness (n.)
    B2 Upper Intermediate

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

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

    Example

    The stars seemed to stretch out into infinity in the dark night sky.

    Example

    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. 2 mathematical value (n.)
    B2 Upper Intermediate Technical Math

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

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

    Example

    In math class, we learned that some sequences of numbers go toward infinity.

    Example

    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'.
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  1. 3 the symbol (n.)
    C1 Advanced Technical Math

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

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

    Example

    The professor wrote the symbol for infinity on the chalkboard.

    Example

    The lemniscate, commonly known as the infinity symbol, was first introduced in a mathematical context during the seventeenth century.
    • lemniscate
  2. 4 optics/distance (n.)
    C2 Proficiency Technical Science

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

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

    Example

    When the camera lens is set to infinity, distant mountains will be in focus.

    Example

    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'.

Origin

From Middle English infinite, from Old French infinité, from Latin īnfīnitās (“unlimitedness”), from negative prefix in- (“not”), + fīnis (“end”), + noun of state suffix -tās.

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