fourth Meaning, Definition & Usage

  1. noun following the third position; number four in a countable series
  2. noun one of four equal parts
    twenty-five percent; fourth part; one-quarter; quartern; one-fourth; quarter.
    • a quarter of a pound
  3. noun the musical interval between one note and another four notes away from it
  4. adjective satellite coming next after the third and just before the fifth in position or time or degree or magnitude
    4th; quaternary.
    • the quaternary period of geologic time extends from the end of the tertiary period to the present
  5. adverb in the fourth place
    fourthly.
    • fourthly, you must pay the rent on the first of the month

WordNet

Fourth adjective
Etymology
OE. fourthe, ferthe, feorthe, AS. feór&edh;a, fr. feówer four.
Definitions
  1. Next in order after the third; the ordinal of four.
  2. Forming one of four equal parts into which anything may be divided.
Fourth noun
Definitions
  1. One of four equal parts into which one whole may be divided; the quotient of a unit divided by four; one coming next in order after the third.
  2. (Mus.) The interval of two tones and a semitone, embracing four diatonic degrees of the scale; the subdominant of any key.

Webster 1913