Pronunciation: (fifth or, often, fith),[key] —adj. 1. next after the fourth; being the ordinal number for five.
2. being one of five equal parts.
3. Auto.of, pertaining to, or operating at the gear transmission ratio at which the drive shaft speed is greater than that of fourth gear for a given engine crankshaft speed: fifth gear.
—adv. in the fifth place; fifthly.
—n. 1. a fifth part, esp. of one (1/5).
2. the fifth member of a series.
3. a fifth part of a gallon of liquor or spirits; 4/5 of a quart (about 750 milliliters).
4. Auto.fifth gear.
5. Music. a. a tone on the fifth degree from another tone (counted as the first).
b. the interval between such tones.
c. the harmonic combination of such tones.
6. take the Fifth,Informal.to decline on the basis of the Fifth Amendment to the U.S. Constitution to answer a question when testifying.