Fifth
Part of speech: adjective
Definition: The ordinal form of the number five.
Part of speech: noun
Definition: The person or thing in the fifth position. One of five equal parts of a whole. The fifth gear of an engine. A quantity of liquor equal to one-fifth of a gallon. The musical interval between one note and another five tones higher.
Example sentence: There'd never been a more advantageous time to be a criminal in America than during the 13 years of Prohibition. At a stroke, the American government closed down the fifth largest industry in the United States - alcohol production - and just handed it to criminals - a pretty remarkable thing to do.
Ordinal
Part of speech: adjective
Definition: Of a number, indicating position in a sequence.
Part of speech: noun
Definition: An ordinal number such as first, second and third.