fifth

1. The person or thing in the fifth position.
2. One of five equal parts of a whole.
3. The fifth gear of an engine.
4. A quantity of liquor equal to one-fifth of a gallon, or, more commonly, 750 milliliters (that is, three quarters of a liter).
5. The musical interval between one note and another seven semitones higher (the fifth note in the major/minor scale)
6. The fifth voice in a polyphonic melody.

1. To support something fifth, after four others have already done so.
2. To divide by 5, equates to multiplying a denominator by 5

adjective

The ordinal form of the number five.