Fifth

Fifth is the ordinal form of the number five. It denotes a position in a sequence, such as the fifth day or the fifth item, and it can describe a one-fifth portion when a whole is divided into five equal parts. The term is formed from the word five plus the usual English ordinal suffix -th; its spelling and pronunciation reflect the language’s historical development.

In mathematics and everyday measurement, a fifth means one part of five equal parts, or 1/5 of a quantity. This fractional sense is common when discussing portions, ratios, or distributions that are divided into five equal units.

The word appears in several legal and cultural contexts. In the United States, the Fifth Amendment to the Constitution provides protections related to due process and self-incrimination, leading to the phrase “pleading the Fifth” to avoid answering questions.

In music, a fifth refers to the interval between two notes with a frequency ratio of approximately 3:2. The perfect fifth is a fundamental harmonic relation and is central to many scales, chords, and tuning systems.

A fifth is also a traditional bottle size for liquor in the United States. Historically defined as one-fifth of a U.S. gallon, a fifth typically holds about 750 milliliters.

Other uses include ranking positions (fifth place) in competitions and various figurative expressions involving fives in social, mathematical, or organizational contexts.