Definition of "fifth" in English

adjective

1. The ordinal form of the number five.

noun

1. (ellipsis or nominalization) The person or thing in the fifth position.

2. One of five equal parts of a whole: one-fifth.

3. (US) A quantity of liquor equal to one-fifth of an American gallon, or, more commonly, 750 milliliters (that is, three quarters of a liter).

4. (music) The musical interval between one note and another five scale degrees higher (the fifth note in a scale)

5. The fifth voice in a polyphonic melody.

verb

1. (music) To sing in the fifth voice in a polyphonic melody.

2. (transitive, informal) To support something fifth, after four others have already done so.

3. (transitive, nonstandard) To divide by five.