ENGLISH
REFERENCE

eighth

num. · n. · v.
US //ˈeɪtθ// UK //ˈeɪtθ// eighth
  1. 1 position in a sequence (num.)
    A2 Elementary

    coming after the seventh and before the ninth.

    the ordinal number matching the cardinal number eight in a sequence.

    Example

    This is the eighth time I have tried to call the bank today.

    Example

    The eighth chapter provides a comprehensive summary of the research findings, bridging the gap between the initial hypothesis and the final data analysis.

  2. 2 a fraction (n.)
    B1 Intermediate Math

    one of eight equal parts of a whole.

    one of eight equal parts into which something is or may be divided.

    Example

    He cut the pizza into slices, and I ate an eighth of it.

    Example

    The carpenter carefully measured an eighth of an inch to ensure the cabinet door would close perfectly against the frame.

  3. 3 music interval (n.)
    B2 Upper Intermediate Music

    the distance between one musical note and the next note with the same name.

    an interval of an octave, representing the distance between one musical pitch and another with double its frequency.

    Example

    The singer struggled to reach the high note an eighth above the melody.

    Example

    The composition requires the pianist to play a series of rapid eighths, demanding significant finger strength and precise timing.
  4. 4 drug measurement (n.)
    C1 Advanced Slang

    a small amount of a drug, usually weighing about 3.5 grams.

    a unit of measurement for illicit drugs, specifically one-eighth of an ounce.

    Example

    He was arrested for carrying an eighth of cannabis in his pocket.

    Example

    The dealer was known for selling an eighth at a higher price than the market average, claiming his product was of superior quality.

  5. 5 to divide by eight (v.)
    C2 Proficiency Technical Math

    to divide something into eight parts.

    to divide a quantity or object by eight. Transitive use.

    Example

    The total cost was eighthed so that each partner paid an equal share.

    Example

    In this specific calculation, the initial value must be eighthed before the final coefficient is applied to the result.

Origin

Inherited from Middle English eightethe, from Old English eahtoþa, from Proto-Germanic *ahtudô; equivalent to eight + -th (ordinal suffix).

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

Last updated June 19, 2026