ENGLISH
REFERENCE

twentieth

num. · n.
US //ˈtwɛniəθ// UK //twˈɛntiəθ// twen·ti·eth
  1. 1 position in a series (num.)
    A2 Elementary

    coming after the nineteenth and before the twenty-first.

    the ordinal form of the number twenty, indicating a position in a sequence.

    Example

    She celebrated her twentieth birthday with a small party for her friends.

    Example

    The twentieth century saw more rapid technological advancement than any previous era in human history.
    • 20th
  2. 2 a fractional part (n.)
    B1 Intermediate Math

    one of twenty equal parts of a whole.

    one of twenty equal parts into which a whole is or may be divided.

    Example

    A twentieth of the budget was spent on office supplies.

    Example

    The researcher noted that only a twentieth of the participants reported experiencing any significant side effects during the initial trial phase.
    • one twentieth
Origin

From earlier twenteth, twentith, from Middle English twentithe, twentiþe, from Old English twēntigoþa. Equivalent to twenty + -eth. Etymological notes twentith, twenteth is the expected development from Middle English twentithe, but in time, the opaque twent- was replaced by a more transparent twenty-, resulting in modern twentieth (in the speech varieties this occurred in, the weak vowel in the final syllable of twenteth, twentith was clearly distinct from that in twenty); similar processes explain the modern pronunciation of thirtieth, fourtieth, etc. This analogy was assisted by synizetic pronunciations of words such as carrying, which allowed twenteth, twentith to be interpreted as contractions of twentieth.

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

Last updated June 20, 2026